MedWorm.com provides a medical RSS filtering service. Over 6000 RSS medical sources are combined and output via different filters. This feed contains the latest items from the 'Electrophoresis' source. Sat, 20 Mar 2010 16:01:16 +0100 http://www.medworm.com/index.php?rid=3382054&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900717 This study presents the dielectrophoretic (DEP) assembly of multi-walled carbon nanotubes (MWCNTs) between curved microelectrodes for the purpose of trapping polystyrene microparticles within a microfluidic system. Under normal conditions, polystyrene particles exhibit negative DEP behaviour and are repelled from microelectrodes. Interestingly, the addition of MWCNTs to the system alters this situation in two ways: first, they coat the surface of particles and change their dielectric properties to exhibit positive DEP behaviour; second, the assembled MWCNTs are highly conductive and after the deposition serve as extensions to the microelectrodes. They establish an array of nanoelectrodes that initiates from the edge of microelectrodes and grow along the electric field lines. These nanoelec... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3382054 Thu, 18 Mar 2010 00:00:00 +0100 3382054 http://www.medworm.com/index.php?rid=3382053&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900736 This article introduces a novel particle separation technique in DC electrokinetic flow through a planar double-spiral microchannel. The continuous separation arises from the cross-stream dielectrophoretic motion of particles induced by the non-uniform electric field inherent to curved channels. Specifically, particles are focused by DEP to one sidewall of the first spiral, and then dielectrophoretically deflected toward the other sidewall of the second spiral at a particle-dependent rate, leading to focused particle streams along different flow paths. This DEP-based particle separation technique is demonstrated in an asymmetric double-spiral microchannel by continuously separating a mixture of 5/10 [mu]m particles and 3/5 [mu]m particles. (Source: Electrophoresis) Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3382053 Thu, 18 Mar 2010 00:00:00 +0100 3382053 http://www.medworm.com/index.php?rid=3382052&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200100037 CE is a high-resolution separation technique broadly used in the biotechnology industry for carbohydrate analysis. The standard sample preparation protocol for CE analysis of glycans released from glycoproteins generally requires derivatization times of overnight at 37°C, using [ge]100 fold excess of fluorophore reagent, 8-aminopyrene-1,3,6-trisulfonic-acid, if the sample is unknown, or it is a regulated biotherapeutic product, possibly containing terminal sialic acid(s). In this paper, we report on significant improvements for the standard CE sample preparation method of glycan analysis. By replacing the conventionally used acetic acid catalyst with citric acid, as low as 1:10 glycan to fluorophore molar ratio (versus the typical 1:[ge]100 ratio) maintained the >95% derivatization yield ... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3382052 Thu, 18 Mar 2010 00:00:00 +0100 3382052 http://www.medworm.com/index.php?rid=3382051&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900772 In this study, a new method is suggested and demonstrated for dispensing a droplet on the top plate with an inverted geometry by using electric field. The process of dispensing droplets consists of two stages: (i) formation of liquid bridge by moving up the charged fluid mass using the electrostatic force between the charges on the fluid mass and the induced charges on the substrate and (ii) its break-up by the motion of the top plate. Different from conventional electrohydrodynamic methods, electric induction enables the droplets to be dispensed on various surfaces including non-conducting substrate. The use of capillarity with an inverted geometry removes the need of external pumps or elaborates control for constant flow feed. The droplet diameter has been characterized as a function of ... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3382051 Thu, 18 Mar 2010 00:00:00 +0100 3382051 http://www.medworm.com/index.php?rid=3345864&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900659 Anthracyclines are chemotherapeutic drugs that are broadly used in the treatment of various types of solid cancers and leukemia. Herein, we report on a novel analytical method for intracellular accumulation of anthracyclines using MEKC/LIF detection. An aqueous separation system permitted the injection of cell lysates directly into the capillary. The MEKC migrating solution was made up of borate buffer at pH 9.22 containing sodium taurodeoxycholate, (2-hydroxypropyl)-[gamma]-CD, and SDS. The anthracyclines, Doxorubicin (DOX) and epirubicin (EPI) were detected by LIF using a Nd:YAG laser (532 nm) or an argon ion laser (488 nm) for excitation. Two cell lines, human humerus tumor cells (RDES) and human lung tumor cells (A549), were treated with a mixture of the two anthracyclines for fixed pe... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3345864 Tue, 09 Mar 2010 00:00:00 +0100 3345864 http://www.medworm.com/index.php?rid=3345863&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900766 2-DE is a fundamental technology used in proteomics research. However, despite its high capacity to simultaneously separate several proteins for subsequent identification and quantitative comparison studies, a drawback for this technique is its limited reproducibility, especially when comparing data from different laboratories. 2-DE-related variability can be broadly divided into two categories: experimental and post-experimental. Experimental variability depends on physical and chemical parameters, whereas post-experimental variability arises when gels are analyzed by different software packages, particularly when different workflows are followed. In this paper, we compared the analysis performance of two software packages, Delta2D and Proteomweaver, using both standard and experimental g... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3345863 Tue, 09 Mar 2010 00:00:00 +0100 3345863 http://www.medworm.com/index.php?rid=3337833&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900422 A fast and precise analysis of the synthetic peptide buserelin in urine using CZE-ESI-MS method has been demonstrated. Formic acid at 50 mmol/L concentration served as backgroud electrolyte in CZE stage and it is compatible with MS detection in positive ionization mode. Two injection modes were tested, i.e. pressure (50 mbar for 5 s) and electrokinetic injection (5 kV for 5 s), of which electrokinetic injection provided better calibration parameters. Buserelin LODs were 0.47 [mu]g/mL in water and 0.63 [mu]g/mL in ten times diluted urine samples using pressure injection, while they were 0.32 [mu]g/mL in water and 0.34 [mu]g/mL in ten times diluted urine samples using electrokinetic injection. Repeatability of buserelin migration times was below 6% (pressure injection mode) and 1% (electroki... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3337833 Fri, 05 Mar 2010 00:00:00 +0100 3337833 http://www.medworm.com/index.php?rid=3337832&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900448 A CE-TOF MS proteomic approach was applied for the analysis of hydrolyzates from complex soybean protein mixtures. After CE-TOF MS method development, the new approach provided the simultaneous analysis of more than 150 peptides from the soybean protein fraction soluble in ACN-water (80/20 v/v). The method is fast (about 30 min of analysis per sample) and is characterized by a relatively low running cost. The approach was used to study the substantial equivalence between a genetically modified variety of soybean compared with its traditional counterpart. No significant differences were found between the two studied soybeans based on the protein fraction studied. The capacity of the CE-TOF MS method to analyze complex mixtures of peptides in short times opens interesting possibilities in th... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3337832 Fri, 05 Mar 2010 00:00:00 +0100 3337832 http://www.medworm.com/index.php?rid=3337831&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900521 Methodology is presented which greatly improves the sensitivity of ganglioside analysis by CE/MS without compromising separation efficiency. In this method, non-volatile additives were removed, where possible, to reduce ion suppression. Specifically, [alpha]-CD, used to break up ganglioside micelle formation, was replaced with isopropyl alcohol. To reduce ion suppression from sodium ions, ammonium borate was substituted for sodium borate in the preparation of borate buffer. Because borate anions were found to be essential for CE separation, a liquid-junction/low-flow interface was employed to restrict borate anions from entering the ESI ion source. With proper control over the EOF in the connecting capillary, borate anions were controlled to migrate away from the ESI ion source. With these... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3337831 Fri, 05 Mar 2010 00:00:00 +0100 3337831 http://www.medworm.com/index.php?rid=3337830&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900536 In this study, the N-methylpolyvinylpyridinuim polymer has for the first time been used as a silica surface modifier for CE in combination with ESI MS (CE-ESI-MS). The compatibility for ESI-MS was demonstrated by the analysis of peptides and protein digests. The N-methylpolyvinylpyridium surface interacts electrostatically with the ionized silanol groups, giving a cationic surface with a reversed EOF. The surface modifier gave rapid and repeatable separations of peptides, proteins and protein digests at acidic pH for more than 4 h of continuous use. The CE separation yielded peak efficiencies of up to 4.3×105 plates/m. The surface coating is highly compatible with ESI and facilitates the separation and analysis of complex peptide mixtures as shown by the analysis of BSA digests. (Source: ... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3337830 Fri, 05 Mar 2010 00:00:00 +0100 3337830 http://www.medworm.com/index.php?rid=3337829&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900629 This article describes a method for the separation and determination of nine drugs of abuse in human urine, including amphetamines, cocaine, codeine, heroin and morphine. This method was based on SPE on a strong cation exchange cartridge followed by CEC-MS. The CEC experiments were performed in fused silica capillaries (100 [mu]m×30 cm) packed with a 3 [mu]m cyano derivatized silica stationary phase. A laboratory-made liquid junction interface was used for CEC-MS coupling. The outlet capillary column was connected with an emitter tip that was positioned in front of the MS orifice. A stable electrospray was produced at nanoliter per minute flow rates applying a hydrostatic pressure (few kPa) to the interface. The coupling of packed CEC columns with mass spectrometer as detector, using a li... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3337829 Fri, 05 Mar 2010 00:00:00 +0100 3337829 http://www.medworm.com/index.php?rid=3337828&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900635 CE-ESI-MS and CE-ICP-MS were implemented for studying three phytosiderophores (mugineic acid, epi-mugineic acid and deoxymugineic acid) and their metal complexes. Free ligands and ferric complexes were analyzed using the first methodology, while six free metals (Co(II), Cu(II), Fe(III), Mn(II), Ni(II) and Zn(II)) together with the corresponding complexes were investigated by the latter technique. CE separation was realized at a voltage of +25 kV employing a BGE containing 20 mM ammonium bicarbonate at pH 7.2. Both techniques revealed limits of detection in the high nM to low [mu]M range. Standard additions to hydroponic samples of H. distichon, cv. Bodega (spring barley) showed regression coefficients for the metal-ligand complexes ranging from 0.984 to 0.999. Additionally, results of a co... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3337828 Fri, 05 Mar 2010 00:00:00 +0100 3337828 http://www.medworm.com/index.php?rid=3337827&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900649 The influence of the BGE composition, including the addition of a single-isomer sulfated [beta]-CD derivative, on the ionization performance of the model compound carvedilol in NACE-ESI-MS was studied using an alternative infusion method. This approach employs voltage-induced infusion of the BGE containing the analyte, and takes into account the effects of variations in EOF and effective analyte mobility on the ESI-MS intensity. First, the optimal composition of the sheath liquid for CE-MS in terms of signal abundance and stability was determined. The BGE ammonium formate, acetate, and camphorsulfonate were found to have similar effects on analyte ionization. Addition of single-isomer sulfated [beta]-CD derivatives (available as sodium salt) to the BGE revealed that the anionic CD derivati... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3337827 Fri, 05 Mar 2010 00:00:00 +0100 3337827 http://www.medworm.com/index.php?rid=3321593&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900513 This study describes an analytical strategy based on CE for detecting intact HBOCs in plasma samples collected for doping control. On-capillary detection was performed by UV/Vis at 415 nm, which offered detection selectivity for hemoproteins (such as hemoglobin and HBOCs). On-line ESI-MS detection with a TOF analyzer was further used to provide accurate masses on CE peaks and to confirm the presence of HBOCs. An immunodepletion sample preparation step was mandatory prior to analysis, in order to remove most abundant proteins that interfered with CE separation and altered the ESI process. This analytical method was successfully applied to plasma samples enriched with Oxyglobin®, a commercially available HBOC used for veterinary purposes. Detection limits of 0.20 and 0.45 g/dL were achieved... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3321593 Mon, 01 Mar 2010 00:00:00 +0100 3321593 http://www.medworm.com/index.php?rid=3321592&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900430 Phosphatidylethanol (Peth), a group of aberrant phospholipids formed in cell membranes in the presence of ethanol, has been recently proposed as biomarker of chronic alcohol abuse. The aim of this study was to develop a new analytical method, based on NACE online coupled with a mass spectrometer for the analysis of Peth in blood. For this purpose an ion-trap mass spectrometer equipped with an orthogonal ESI source operating in negative ion mode was used. An alkaline solution of ammonium acetate 5 mM (pH 9) in water/methanol (MeOH) (80:20 v/v) was delivered as coaxial sheath liquid. All experiments were performed using an uncoated fused-silica capillary (90 cm×75 [mu]m id). The effects of variable percentages of ACN, MeOH, 2-propanol, dichloromethane, along with variable concentrations of ... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3321592 Mon, 01 Mar 2010 00:00:00 +0100 3321592 http://www.medworm.com/index.php?rid=3321591&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900517 An interface for CE-ESI-MS that decouples both the electrical and the solution flow rate requirements of the separation and ionization processes is presented. The interface uses a tapered and beveled stainless steel hollow needle surrounding the separation capillary terminus so that the inside of the electrode acts as the CE outlet vial and the outside tip acts as the electrospray emitter. No capillary pre-treatment is required, enabling the use of capillaries with any type of surface modification. A chemical modifier solution is introduced through a second capillary connected to the needle via a tee junction and can be used to improve the compatibility of the CE BGE with electrospray. The flow rate of modifier solution can be as low as 0.1 [mu]L/min, much less than that in a typical sheat... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3321591 Mon, 01 Mar 2010 00:00:00 +0100 3321591 http://www.medworm.com/index.php?rid=3321590&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900585 In this study, [alpha]-chymotrypsin (CT), a serine protease, was chosen as a model compound. Chymostatin is a naturally occurring peptide aldehyde binding to CT through a hemiacetal bond and electrostatic interaction. First, a CE separation was developed, which allows the analysis of [alpha]-CT and a chymotrypsin-chymostatin complex under MS-compatible conditions. The use of neutral-coated CE capillaries was mandatory to reduce analyte-wall interactions. ESI-quadrupole ion trap-MS was worked out to demonstrate the selective drug release after CID. Fragmentation of the drug-enzyme complex was monitored in dependence from the excitation energy in the ion trap, leading to the V50 voltage that enables 50% complex fragmentation as a reference value for chymotrypsin-chymostatin complex. A stable... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3321590 Mon, 01 Mar 2010 00:00:00 +0100 3321590 http://www.medworm.com/index.php?rid=3321589&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900621 A fast and reliable method based on CZE coupled to Q-TOF MS for the analysis of methylated melamines is presented. Experiments with UV detection were performed using BGE containing formic acid and TFA to optimize electrophoretic conditions and to achieve baseline separation. Employing a TFA-based electrolyte containing 80% ACN and MS detection, nine different methyl melamines were determined in real samples, which were produced by catalytic hydrogenation of melamine/formaldehyde reaction mixtures. The use of a Q-TOF MS resulted in LOD better than 0.01 mg/L for all compounds and high mass accuracy with mass errors lower than 2.3 ppm. (Source: Electrophoresis) Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3321589 Mon, 01 Mar 2010 00:00:00 +0100 3321589 http://www.medworm.com/index.php?rid=3282976&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900493 Reversible protein phosphorylation plays a critical role in liver development and function. Comprehensively cataloging the phosphoproteins and their phosphorylation sites in human liver tissue will facilitate the understanding of physiological and pathological mechanisms of liver. Owing to lacking of efficient approach to fractionate phosphopeptides, nanoflow-RPLC with long-gradient elution was applied to reduce the complexity of the phosphopeptides in this study. Two approaches were performed to further improve the coverage of phosphoproteome analysis of human liver tissue. In one approach, ten-replicated long-gradient LC-MS/MS runs were performed to analyze the enriched phosphopeptides, which resulted in the localization of 1080 phosphorylation sites from 495 proteins. In another approac... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3282976 Thu, 18 Feb 2010 00:00:00 +0100 3282976 http://www.medworm.com/index.php?rid=3282978&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900525 Protein-protein conjugates formed by carbodiimide crosslinking reactions have been analyzed for the first time using CE. Lysozyme and BSA were chosen as model proteins to study the efficacy of N-(3-dimethylaminopropyl)-N-ethylcarbodiimide and N-hydroxysuccinimide as crosslinkers. Detection of the molecular mass increase was checked by SDS-PAGE. Commercially available, PVA-coated capillaries showed appropriate selection, while phospho-deactivated and dynamic PVA-coated capillaries did not give suitable resolution. CE was found to be an efficient tool to characterize homo- (lysozyme-lysozyme) and hetero- (lysozyme-BSA) protein coupling by suitable variations of electrophoretic mobilities. (Source: Electrophoresis) Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3282978 Wed, 17 Feb 2010 00:00:00 +0100 3282978 http://www.medworm.com/index.php?rid=3282977&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900423 The low molecular weight proteins can provide a lot of valuable information of biomarkers. To study these proteins, the high abundance and high molecular weight proteins must be removed prior to analysis. In this work, a simple and inexpensive disc SDS-PAGE to extract low molecular weight proteins from human serum and cutoff proteins larger than 30 kDa was developed. Some experimental conditions were examined. The experimental results obtained by plate SDS-PAGE and MALDI-TOF MS showed that the molecular weight of extracted proteins was about in the range from 0.3 to 28 kDa. Some experiments, including precipitation of proteins in organic solvents, SPE and cytochrome C test, were carried out and the experimental results demonstrated successful recovery of proteins/peptides with molecular we... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3282977 Wed, 17 Feb 2010 00:00:00 +0100 3282977 http://www.medworm.com/index.php?rid=3269347&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900457 A generalized preparation procedure of open tubular (OT) molecule imprinted polymer (MIP) columns is proposed for a number of templates with acidic functionality such as profen drugs and others. The template (S-enantiomer) was mixed with methacrylic acid, ethylene glycol dimethacrylate and 4-styrenesulfonic acid, dissolved in a porogen mixture of ACN/2-propanol (9/1), and incubated in a pretreated and silanized fused silica capillary by the thermal non-covalent polymerization procedure. The whole preparation procedure was exactly the same for all the MIP capillaries except for the selection of template. Nevertheless, the morphologies of the MIP layers were markedly variant depending upon the choice of template. The separation efficiency of each OT-MIP column for chiral separation of R- and... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3269347 Fri, 12 Feb 2010 00:00:00 +0100 3269347 http://www.medworm.com/index.php?rid=3269346&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900508 In this study, it was observed that achiral separations using MEKC and PEM coatings individually resulted in partial resolution of eight very similar aryl ketones when the molecular micelle (sodium poly(N-undecanoyl-L-glycinate)) concentration was varied from 0.25 to 1.00% w/v and the bilayer number varied from 2 to 4. However, when MM separation was introduced, baseline resolution was achieved for all eight analytes. In the case of chiral separations, temazepam, aminoglutethimide, benzoin, benzoin methyl ether, and coumachlor were separated using the three separation techniques. For chiral separations, the chiral molecular micelle, sodium poly(N-undecanoyl-L-leucylvalinate), was employed at concentrations of 0.25-1.50% w/v for both MEKC and PEM coatings. Overall, the results revealed part... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3269346 Fri, 12 Feb 2010 00:00:00 +0100 3269346 http://www.medworm.com/index.php?rid=3269345&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900515 A new method, pressurized CEC with end-column amperometric detection using carbon paste electrode, has been developed for the separation and determination of five phenolic xenoestrogens in chicken eggs and milk powder samples. Efficient separation of five analytes was performed by pressurized CEC using a mobile phase consisting of 60% v/v ACN and 40% v/v Tris buffer (5 mmol/L, pH 8.0), +6 kV of applied voltage and 7.0 MPa of supplementary pressure. Detection limits of 50, 5, 2, 10 and 20 ng/mL for pentachlorophenol, bisphenol-A, 2,4-dichlorophenol, 4-tert-octylphenol and 4-nonylphenol, respectively, were achieved using carbon paste electrode as working electrode and +0.8 V as detection potential. Matrix solid phase dispersion extraction method had been employed during sample preparation pr... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3269345 Fri, 12 Feb 2010 00:00:00 +0100 3269345 http://www.medworm.com/index.php?rid=3266288&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900591 Histamine poisoning is caused by the consumption of fish and other foods that harbor bacteria possessing histidine decarboxylase activity. With the aim of preventing histamine formation, highly specific mass spectral fingerprints were obtained from the 16 major biogenic amine-producing enteric and marine bacteria by means of MALDI-TOF MS analysis. All bacterial strains analyzed exhibited specific spectral fingerprints that enabled its unambiguous differentiation. This technique also identified peaks common to certain bacterial groups. Thus, two protein peaks at m/z 4182±1 and 8363±6 were found to be present in all Enterobacteriaceae species analyzed except for Morganella morganii. Peaks at m/z 3635±1 and 7267±2 were specific to both M. morganii and Proteus spp. Biogenic amine-forming P... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3266288 Fri, 12 Feb 2010 00:00:00 +0100 3266288 http://www.medworm.com/index.php?rid=3266291&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900578 An optimized capacitively coupled contactless conductivity detector for microchip electophoresis is presented. The detector consists of a pair of top-bottom excitation electrodes and a pair of pickup electrodes disposed onto a very thin plastic microfluidic chip. The detection cell formed by the electrodes is completely encased and shielded in a metal housing. These approaches allow for the enhancement of signal coupling and extraction from the detection cell that result in an improved signal-to-noise-ratio and detection sensitivity. The improved detector performance is illustrated by the electrophoretic separation of six cations (NH4+, K+, Ca2+, Na+, Mg2+, Li+) with a detection limit of approximately 0.3 [mu]M and the analysis of the anions (Br-, Cl-, NO2-, NO3-, SO42-, F-) with a detecti... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3266291 Thu, 11 Feb 2010 00:00:00 +0100 3266291 http://www.medworm.com/index.php?rid=3266290&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900596 Enantioseparation of tartaric acid by ligand exchange CE with a Cu(II)-D-quinic acid system was studied. Racemic tartaric acid was enantioseparated by ligand exchange CE using BGEs containing relatively low Cu(II)-D-quinic acid molar ratios ranging from 1:1 to 1:3 and high molar ratios ranging from 1:8 to 1:12 but was not enantioseparated using BGEs with medium molar ratios ranging from 1:4 to 1:6. While the migration order of D-tartaric acid was prior to L-tartaric acid at the lower Cu(II)-D-quinic acid molar ratios, the enantiomer migration order was reversed at the higher molar ratios. These results were compared with those for Ni(II)-D-quinic acid system. The molar ratio dependence of enantiomer migration order can be attributed to a change in the coordination structure of Cu(II) ion w... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3266290 Thu, 11 Feb 2010 00:00:00 +0100 3266290 http://www.medworm.com/index.php?rid=3266289&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900598 In this article, we describe the analysis of aptamers for Hg2+ ions through CE with LIF (CE-LIF) detection using 2% poly(ethylene oxide) solutions containing OliGreen (fluorophore). In the presence of an EOF, DNA strands migrating against the EOF were detected at the cathode end. Four DNA strands - T33, T5C28, T5C5T23, and T15C5T13 - could not be separated through CE-LIF in the absence of Hg2+. At 0.3 mM Hg2+, however, all four were partially separated within 20 min, with SDs of the migration times all being less than 2.5%. From the CE, fluorescence, and ellipticity data, we concluded that the conformations of these four DNA strands all changed from random-coil to folded structures as a result of T-Hg2+-T bonding. In addition, we found that this CE approach provided different electropherog... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3266289 Thu, 11 Feb 2010 00:00:00 +0100 3266289 http://www.medworm.com/index.php?rid=3262155&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900700 A neutral naphthyl methacrylate-based monolith (NMM) was introduced for RP-CEC of various aromatic compounds via hydrophobic and [pi] interactions. It was characterized over a wide range of elution conditions to gain insight into its RP retention mechanism toward the various solute probes under investigation. First, the NMM column exhibited cathodal EOF at various mobile phase compositions and pH suggesting that although the NMM column is void of fixed charges, it acquires a negative zeta potential. It is believed that the negative zeta potential is imparted by the adsorption of mobile phase ions to the NMM surface. The NMM column exhibited [pi]-[pi] interactions in addition to hydrophobic interactions due to the aromatic and nonpolar nature of its naphthyl ligands. In all cases, the reten... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3262155 Wed, 10 Feb 2010 00:00:00 +0100 3262155 http://www.medworm.com/index.php?rid=3215724&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900615 In the present study, restriction site-amplified polymorphism (RSAP) markers were used to examine the genetic variability of Schistosoma japonicum isolates from different endemic provinces in mainland China. Of the 45 pairs of primers screened, 10 RSAP markers showed a clear banding pattern with good resolution; however, only six exhibited a polymorphism among different isolates. Among six RSAP markers, one pair of primers (R8+R10) was able to differentiate male and female parasites, and amplified one constant specific band for female S. japonicum isolates. The specific band was recovered, re-amplified and sequenced, and a sequence of 162 bp was obtained. Based on this sequence, a pair of specific primers was designed and used to develop sequence characterized amplified region (SCAR)-PCR a... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3215724 Thu, 28 Jan 2010 00:00:00 +0100 3215724 http://www.medworm.com/index.php?rid=3215729&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900538 A rapid and sensitive DNA targets detection using enzyme amplified electrochemical detection (ED) based on microchip was described. We employed a biotin-modified DNA, which reacted with avidin-conjugated horseradish peroxidase (avidin-HRP) to obtain the HRP-labeled DNA probe and hybridized with its complementary target. After hybridization, the mixture containing dsDNA-HRP, excess ssDNA-HRP, and remaining avidin-HRP was separated by MCE. The separations were performed at a separation voltage of +1.6 kV and were completed in less than 100 s. The HRP was used as catalytic labels to catalyze H2O2/o-aminophenol reaction. Target DNA could be detected by the HRP-catalyzed reduction with ED. With this protocol, the limits of quantification for the hybridization assay of 21- and 39-mer DNA fragmen... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3215729 Wed, 27 Jan 2010 00:00:00 +0100 3215729 http://www.medworm.com/index.php?rid=3215728&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900565 We have employed a high-sensitivity off-line coupled with on-line preconcentration method, cloud-point extraction (CPE)/cation-selective exhaustive injection (CSEI) and sweeping-MEKC, for the analysis of malachite green. The variables that affect CPE were investigated. The optimal conditions were 250 g/L of Triton X-100, 10% of Na2SO4 (w/v), heat-assisted at 60°C for 20 min. We monitored the effects of several of the CSEI-sweeping-MEKC parameters - including the type of BGE, the concentrations of SDS, the injection length of the high-conductivity buffer, and the injection time of the sample - to optimize the separation process. The optimal BGE was 50 mM citric acid (pH 2.2) containing 100 mM SDS. In addition, electrokinetic injection of the sample at 15 kV for 800 s provided both high sep... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3215728 Wed, 27 Jan 2010 00:00:00 +0100 3215728 http://www.medworm.com/index.php?rid=3215727&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900581 ACE was applied to the quantitative evaluation of noncovalent binding interactions between benzo-18-crown-6-ether (B18C6) and several alkali metal ions, Li+, Na+, K+, Rb+ and Cs+, in a mixed binary solvent system, methanol-water (50/50 v/v). The apparent binding (stability) constants (Kb) of B18C6-alkali metal ion complexes in the hydro-organic medium above were determined from the dependence of the effective electrophoretic mobility of B18C6 on the concentration of alkali metal ions in the BGE using a nonlinear regression analysis. Before regression analysis, the mobilities measured by ACE at ambient temperature and variable ionic strength of the BGE were corrected by a new procedure to the reference temperature, 25°C, and the constant ionic strength, 10 mM. In the 50% v/v methanol-water... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3215727 Wed, 27 Jan 2010 00:00:00 +0100 3215727 http://www.medworm.com/index.php?rid=3215726&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900531 This study provides important basic information on Anisakis in this region and suggests that the genus Anisakis has substantial host and geographical distributions. (Source: Electrophoresis) Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3215726 Wed, 27 Jan 2010 00:00:00 +0100 3215726 http://www.medworm.com/index.php?rid=3215725&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900573 The electrophoretic mobility-shift assay (EMSA) is one of the most popular tools in molecular biology for measuring DNA-protein interactions. EMSA, as standardly practiced today, works well for complexes with association binding constants Ka>109 M-1 under normal conditions of salt and pH. Many DNA-protein complexes are not stable enough so that they dissociate while moving through the gel matrix giving smeared bands that are difficult to quantitate reliably. In this work we demonstrate that the addition of the osmolyte triethylene glycol to polyacrylamide gels dramatically stabilizes labile restriction endonuclease EcoRI complexes with nonspecific DNA sequences enabling quantitation of binding using EMSA. The significant improvement of the technique resulting from the addition of osmolytes... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3215725 Wed, 27 Jan 2010 00:00:00 +0100 3215725 http://www.medworm.com/index.php?rid=3197111&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900617 Characterization of PEGs with average molecular masses of up to 2000 has been achieved using MEKC with UV detection. A rapid derivatization procedure with phenyl isocyanate using microwave radiation, in order to introduce chromophore groups in PEGs, has been developed involving a reaction time of 60 s. Different optimized conditions in accordance with the molecular weight have been studied to obtain the oligomer separation. The weight-average molecular mass the number-average molecular mass and the degree of polydispersity (molecular mass distribution) were calculated for the different PEGs obtaining similar results with those certified for standards. A good precision was obtained for characterizing the different oligomers. Ethylene glycol was used as the internal standard for the analysis... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3197111 Fri, 22 Jan 2010 00:00:00 +0100 3197111 http://www.medworm.com/index.php?rid=3197112&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900551 In this study, without using any pumps, we present a simple scheme that controls the ratio of the volumetric flow rate (VFR) of the parallel streams that have highly different hydrophilicity and viscosity. We accomplish this process by using capillarity to drive and merge two streams, and by regulating relative flow resistance to control the VFR ratio. Our results will significantly simplify the control of the VFR ratio for the various biochemical solutions that are used in microfluidic applications. (Source: Electrophoresis) Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3197112 Thu, 21 Jan 2010 00:00:00 +0100 3197112 http://www.medworm.com/index.php?rid=3104458&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900055 A technique for separating and detecting enzyme inhibitors was developed using CE with an enzyme microreactor. The on-column enzyme microreactor was constructed using NdFeB magnet(s) to immobilize alkaline phosphatase-coated superparamagnetic beads (2.8 [mu]m diameter) inside a capillary before the detection window. Enzyme inhibition assays were performed by injecting a plug of inhibitor into a capillary filled with the substrate, AttoPhos. Product generated in the enzyme microreactor was detected by LIF. Inhibitor zones electrophoresed through the capillary, passed through the enzyme microreactor, and were observed as negative peaks due to decreased product formation. The goal of this study was to improve peak capacities for inhibitor separations relative to previous studies, which combin... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3104458 Sat, 19 Dec 2009 00:00:00 +0100 3104458 http://www.medworm.com/index.php?rid=3104468&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900472 A negative detection method for proteins on SDS-PAGE is described. In this method, Eosin Y (EY) was selectively precipitated in the gel background, which is absent from those zones where proteins are located through the formation of a stable water-soluble protein-dye complex. Negative staining of proteins using EY, allows high-sensitivity, low-cost, and simple protocol. The new described method takes less than an hour to complete all the protocol, with a detection limit of 0.5 ng of single protein band. Comparing with imidazole-zinc negative stain, EY dye provides broader linear dynamic range, higher sensitivity and reproducibility, and better obvious contrast between the protein bands or spots and background. Furthermore, the novel technique developed here presented a real practical metho... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3104468 Fri, 18 Dec 2009 00:00:00 +0100 3104468 http://www.medworm.com/index.php?rid=3104467&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900302 A sensitive method for simultaneous determination of azithromycin (AZI), acetylspiramycin (ACE), erythromycin (ERY), and josamycin (JOS) was developed by CE coupled with electrochemiluminescence detection with Ru(bpy)32+. The parameters related to separation and detection were investigated in detail. The four macrolides were well separated and detected within 6 min under the optimized conditions. The LOD (S/N=3) of AZI, ACE, ERY, and JOS were 1.2×10-9, 7.1×10-9, 3.9×10-8 and 9.5×10-8 mol/L, respectively. The LOQ (S/N=10) of AZI, ACE, ERY, and JOS in human urine were 8.2×10-8, 2.5×10-7, 8.9×10-7 and 1.2×10-6 mol/L, respectively. The recoveries of the four macrolides in human urine and pharmaceutical tablet samples were 85.0-104.0% at different concentration levels. (Source: Electrop... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3104467 Fri, 18 Dec 2009 00:00:00 +0100 3104467 http://www.medworm.com/index.php?rid=3104466&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900310 In this study, the CIEF of influenza viruses with UV detection has been developed and subsequently used to test the purification of the virus from the biological samples. The equine and swine influenza viruses present in infected allantoic fluid of specific pathogen free embryonated chicken eggs were precipitated by using PEG 6000 and sodium chloride. The precipitated viruses were centrifuged at 14 000×g, and the impurities of different densities were removed by using the sucrose gradients. The efficiency of the virus purification technique was examined by the CIEF and compared to the results of real-time PCR. The pIs of both influenza viruses were determined. Simultaneously, the CIEF was found to be a suitable method for the rapid testing of the efficiency of the virus purification. (Sou... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3104466 Fri, 18 Dec 2009 00:00:00 +0100 3104466 http://www.medworm.com/index.php?rid=3104465&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900315 CE is a powerful analytical tool used to separate intact biomolecules such as proteins. The coupling of CE with TOF/MS produces a very promising method that can be used to detect and identify proteins in different matrices. This paper describes an efficient, rapid, and simple CE-ESI-TOF/MS procedure for the analysis of endogenous human growth hormone and recombinant human growth hormone without sample preparation. Operational factors were optimized using an experimental design, and the method was successfully applied to distinguish human growth hormone and recombinant human growth hormone in unknown samples. (Source: Electrophoresis) Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3104465 Fri, 18 Dec 2009 00:00:00 +0100 3104465 http://www.medworm.com/index.php?rid=3104464&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900318 Rapid and efficient enantioseparation of halogen aryl alcohols and [beta]-blockers propranolol and pindolol in packed bed CEC (p-CEC) using as-prepared submicron porous silica chiral stationary phases (CSPs) has been achieved. Monodispersed 0.66 and 0.81 [mu]m chiral submicron porous silica spheres were prepared using tetramethoxysilane and hexadecyltrimethylammonium bromide, followed by a hydrothermal treatment method with ammonia-ethanol to expand the pore of silica spheres without changing their spherical morphology. A proper specific surface of ca. 230 m2/g and pore sizes average of 6-8 nm were obtained by this method. The submicron porous silica spheres were modified with mono-6-phenylcarbamoylated [beta]-CD via thiol-en radical addition. They were packed into 9 cm 50 [mu]m id capilla... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3104464 Fri, 18 Dec 2009 00:00:00 +0100 3104464 http://www.medworm.com/index.php?rid=3104463&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900343 In this study, an approach to the enantioseparation of basic drugs by means of NACE with erythromycin lactobionate (EL) belonging to the group of macrolide antibiotics has been investigated. Especially different from the above four classes of antibiotics, there are no reports concerned with the use of macrolides which belong to macrocyclic antibiotics as chiral selectors in CE. In this work EL is first used as a chiral selector in NACE for the enantiomeric separations of two racemic basic drugs that possess high separability consisting of propranolol and duloxetine. Furthermore, EL possesses advantages such as high solubility and low viscosity in the solvent and very weak UV absorption. The chiral separations were achieved using Tris-boric acid as the BGE and methanol as the organic medium... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3104463 Fri, 18 Dec 2009 00:00:00 +0100 3104463 http://www.medworm.com/index.php?rid=3104462&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900394 Ghrelin is a pharmacologically interesting peptide hormone due to its effects on appetite and metabolism. The cationic, octanoylated 28 amino acid peptide has a short biological half-life; thus, prolonged release formulations are of interest. Acylated peptides have been suggested to bind to or be incorporated into liposomes. Formulations based on neutral dipalmitoylphosphatidylcholine (DPPC) liposomes and phosphatidylcholine:cholesterol (70:30 mol%) liposomes, and negatively charged dipalmitoylphosphatidylcholine:dipalmitoylphosphatidylserine (DPPC:DPPS) (70:30 mol%) liposomes (2 mM total lipid concentration) were characterized using ACE. Pre-equilibrium CZE and frontal analysis CE methods circumventing capillary wall adsorption of the peptide and the liposomes and suitable for characteriz... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3104462 Fri, 18 Dec 2009 00:00:00 +0100 3104462 http://www.medworm.com/index.php?rid=3104461&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900417 We introduce here a method for continuous intact cell detection and viability determination of individual trypan blue stained cells by CE with ultraviolet-visible dual-wavelength detection. To avoid cell aggregation or damage during electrophoresis, cells after staining were fixed with 4% formaldehyde and were continuously introduced into the capillary by EOF. The absorbance of a cell at 590 nm was used to determine its viability. An absorbance of two milli-absorbance unit at 590 nm was the clear cut-off point for living and dead Hela cells in our experiments. Good viability correlation between the conventional trypan blue staining assay and our established CE method (correlation coefficient, R2=0.9623) was demonstrated by analysis of cell mixtures with varying proportions of living and de... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3104461 Fri, 18 Dec 2009 00:00:00 +0100 3104461 http://www.medworm.com/index.php?rid=3104460&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900389 This study reports the methodology used to search, select and characterize STR loci on the canine X chromosome using publicly available genome resources and following the current guidelines for human and non-human forensic testing. After several rounds of selection, 12 X-STR markers were optimized for simultaneous co-amplification in a single PCR, and genetic profiles were determined in a sample of 103 unrelated dogs. Mendelian inheritance was verified and mutation rates were assessed using family groups. Alleles that varied in size were sequenced to create a standardized nomenclature proposal based on the number of repeats. All loci conformed to Hardy-Weinberg expectations. The resulting panel showed high forensic efficiency, presenting high values of power of discrimination (in males and... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3104460 Fri, 18 Dec 2009 00:00:00 +0100 3104460 http://www.medworm.com/index.php?rid=3104459&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900424 This study now describes a simple and rapid electrophoretic method that allows detection of degradative enzyme activity directly in whole blood using charge-changing fluorescent peptide substrates. Charge-changing substrates eliminate the need for sample preparation by producing positively charged cleavage fragments that can be readily separated from the oppositely charged fluorescent substrate and blood components by electrophoresis. Two peptide substrates have been developed for pancreatic [alpha]-chymotrypsin and trypsin. For the first substrate, a detection limit of 3 ng for both [alpha]-chymotrypsin and trypsin was achieved in whole rat blood using a 4% agarose gel. This substrate had minimal cross-reactivity with the trypsin-like proteases thrombin, plasmin, and kallikrein. For the s... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3104459 Fri, 18 Dec 2009 00:00:00 +0100 3104459 http://www.medworm.com/index.php?rid=3081981&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900510 This article presents an overview of coupled SPE-CE systems that have been reported in the literature between April 2007 and June 2009. The use of in-line and on-line SPE-CE is covered in this review. Special attention is paid to the use of monoliths and molecularly imprinted polymers in coupled SPE-CE systems. Application-oriented research is discussed in which in-line and on-line SPE-CE systems have been used in biomedical, pharmaceutical, environmental and food analysis. The SPE-CE studies are presented in tables, including information on sample type, SPE sorbent, detection and LOD. Finally, some future developments that may increase the applicability of coupled SPE-CE are highlighted. (Source: Electrophoresis) Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3081981 Sat, 12 Dec 2009 00:00:00 +0100 3081981 http://www.medworm.com/index.php?rid=3081983&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900465 Lab-on-a-chip electrophoresis is becoming increasingly useful for protein analysis, thanks to recent developments in this field. This review is an update of the review we published at the start of 2008 [Peng, Y., Pallandre, A., Tran, N. T., Taverna, M., Electrophoresis 2008, 29, 156-177]. The superiority of polymers for the manufacture of analytical microchips has been confirmed. This trend implies several modifications to the processes previously used with glass/silicon chips and requires a better understanding of the interfacial phenomena of these materials. Significant progress in chip-based techniques for protein analysis has been made in the last 2 years. In addition to advances in traditional electrokinetic modes, counter-flow gradient focusing techniques have emerged as useful metho... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3081983 Fri, 11 Dec 2009 00:00:00 +0100 3081983 http://www.medworm.com/index.php?rid=3081982&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900366 The continued publication from year to year of new MEKC formulations for the analysis of amino acids provides evidence that both CZE and MEKC still have a great power of attraction in this area. The present review intends to cover the literature on MEKC of amino acids from 2007 until present: it has been planned to follow the same format of our previous review (Electrophoresis 2008, 29, 224-236) representing its ideal continuation. In addition to methodological developments, the more recent practical applications of MEKC procedures for the determination of amino acids in different matrices will also be described here as an evidence, once again, of the suitability of this technique on samples of different origin. (Source: Electrophoresis) Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3081982 Fri, 11 Dec 2009 00:00:00 +0100 3081982 http://www.medworm.com/index.php?rid=3070482&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900402 This article reviews the latest advances in the development of analytical methodologies by CE and CEC for the analysis of different groups of antibiotics. CZE and MEKC have been the most employed CE modes. Analytical information on experimental conditions, detection mode, and LOD are provided to the readers. In addition, the main applications performed in the pharmaceutical, biological, food, and environmental fields have been reviewed emphasizing the sample preparation requirements. The publications reviewed cover the period of time from June 2007 to May 2009. (Source: Electrophoresis) Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3070482 Wed, 09 Dec 2009 00:00:00 +0100 3070482 http://www.medworm.com/index.php?rid=3055925&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900365 The use of capillary electromigration methods to analyze foods and food components is reviewed in this work. Papers that were published during the period April 2007 to March 2009 are included following the previous review by García-Cañas and Cifuentes (Electrophoresis, 2008, 29, 294-309). These works include the analysis of amino acids, biogenic amines, peptides, proteins, DNAs, carbohydrates, phenols, polyphenols, pigments, toxins, pesticides, vitamins, additives, small organic and inorganic ions and other compounds found in foods and beverages, as well as those applications of CE for monitoring food interactions and food processing. The use of microchips, CE-MS, chiral-CE as well as other foreseen trends in food analysis are also discussed including their possibilities in the very new ... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3055925 Fri, 04 Dec 2009 00:00:00 +0100 3055925 http://www.medworm.com/index.php?rid=3055924&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900373 This review covers the time period of 2007 until mid-2009 and describes new developments in the field of electrophoretically mediated microanalysis. The review is subdivided in two parts dealing with (i) enzymatic and (ii) derivatization or chemical reactions. A compilation of the relevant literature is given for each part. (Source: Electrophoresis) Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3055924 Fri, 04 Dec 2009 00:00:00 +0100 3055924 http://www.medworm.com/index.php?rid=3055923&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900397 This review article represents the sixth in a series of reviews on CE applied to inorganic analysis, appearing in this journal, and focuses on material published in 2007-2008. As a fundamental review, it examines primarily those documents in which the emphasis is on advances in general CE methodology which are traditionally set on the attainment of higher detection sensitivity and greater preconcentration factors both in capillary and microchip separation formats. Following a major research trend of the previous review period (see A.R. Timerbaev, Electrophoresis 2007, 28, 3420-3425), publications focusing on the quantification of different element species continue to rapidly outpace other applications. A range of practicable separation and detection designs tailor-made to species-selective... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3055923 Fri, 04 Dec 2009 00:00:00 +0100 3055923 http://www.medworm.com/index.php?rid=3055922&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900399 This article describes the most important articles that have been published on amino acid analysis using CE during the period from June 2007 to May 2009. It follows the format of the previous articles of Smith [Electrophoresis 1999, 20, 3078-3083], Prata et al. [Electrophoresis 2001, 22, 4129-4138] and Poinsot et al. [Electrophoresis 2003, 24, 4047-4062; Electrophoresis 2006, 27, 176-194; Electrophoresis 2008, 29, 207-223]. For several years we have presented the new developments in amino acid analysis with CE which describe the use of laser emitting diodes for LIF as well as via MS. In addition, we describe articles concerning clinical studies and neuroclinical applications. (Source: Electrophoresis) Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3055922 Fri, 04 Dec 2009 00:00:00 +0100 3055922 http://www.medworm.com/index.php?rid=3043879&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900482 This article reviews and comments the applications of CE to forensic sciences covering the short period from 2007 until the first months of 2009, being the latest update of two previous review papers covering the years from 2001 to 2004 and from 2005 to 2007. The overview includes the most relevant examples of analytical applications of capillary electrophoretic and electrokinetic techniques in the following fields: (i) illicit and abused drugs, (ii) small ions of forensic interest (iii) proteins and peptides, (iv) forensic deoxyribonucleic acid, (v) dyes and inks. As many as 69 references are quoted. (Source: Electrophoresis) Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3043879 Tue, 01 Dec 2009 00:00:00 +0100 3043879 http://www.medworm.com/index.php?rid=3043880&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900442 The review presents a comprehensive survey of recent developments of high-performance capillary electromigration methods, zone electrophoresis, ITP, IEF, affinity electrophoresis, EKC and electrochromatography, and their application to analysis, preparation and physicochemical characterization of peptides. New approaches to the theoretical description and experimental investigation of electromigration properties of peptides, and to methodology of their separations, such as sample preparation, adsorption suppression, EOF control and detection, are described. New developments in particular CE and CEC modes are reported and several types of their applications to peptide analysis are presented: conventional qualitative and quantitative analysis, determination in biomatrices, monitoring of chem... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3043880 Mon, 30 Nov 2009 00:00:00 +0100 3043880 http://www.medworm.com/index.php?rid=3026000&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900572 Increasing awareness of the importance of cell heterogeneity in many biological and medical contexts is prompting increasing interest in systems that allow single-cell analysis rather than conventional bulk analysis (which provides average values for variables of interest from large numbers of cells). Recently, we presented a microwell chip for long-term, high-throughput single-cell analysis. The chip has proved to be useful for purposes such as screening individual cancer and stem cells for protein/gene markers. However, liquids in the wells can only be added or changed by manually rinsing the chip, or parts of it. This procedure has several well-known drawbacks - including risks of cross-contamination, large dead volumes and laboriousness - but there have been few previous attempts to in... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3026000 Wed, 25 Nov 2009 00:00:00 +0100 3026000 http://www.medworm.com/index.php?rid=3007411&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900333 We developed an on-chip DNA analysis method, in which free-solution transient isotachophoresis (FstITP) were coupled with CGE. Using chloride ions in the sample matrix and HEPES in the background electrolyte, respectively, as the leading and terminating ions, dsDNAs were isotachophoretically preconcentrated in free-solution and then separated in sieving polymer. The coupling of FstITP and CGE enabled higher separation efficiency due to higher preconcentration rate in free-solution. The FstITP-CGE analysis offered adjustable signal intensities by varying sample injection time. With the maximum sample loading volume, the LOD of the FstITP-CGE analysis was determined to be 0.24 ng/mL by confocal laser-induced fluorescence detection. The FstITP-CGE method is simple, robust and flexible, thus w... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3007411 Wed, 18 Nov 2009 00:00:00 +0100 3007411 http://www.medworm.com/index.php?rid=3007410&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900334 Microchip-based bead-packed columns for electrochromatography are described for several types of stationary phases. Chromatography columns 2 mm in length were used for the separation of proteins and peptides by size- and ion-exchange modes of separation, respectively. In size-exclusion electrochromatograpgy, FITC-IgG and FITC-insulin were baseline resolved in less than 10 s, with efficiencies of up to 139,000 plates/m for FITC-insulin. In strong cation-exchange electrochromatography, a mixture of three fluorescently labeled peptides was baseline resolved in less than 40 s, with efficiencies up to 400,000 plates/m. The RSD for the analytes retention times were (Source: Electrophoresis) Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3007410 Wed, 18 Nov 2009 00:00:00 +0100 3007410 http://www.medworm.com/index.php?rid=3007409&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900345 Synchronized continuous-flow zone electrophoresis is a recently demonstrated tool for performing electrophoretic fractionation of a complex sample. The method resembles free flow electrophoresis, but unlike in that technique, no mechanical fluid pumping is required. Instead, fast electrokinetic flow switching is used to produce complex stream patterns, which results in lateral separation of components in a separation chamber. Here a solution is presented which allows for simultaneous collection of two fractions in synchronized continuous-flow zone electrophoresis. The method is demonstrated on a model mixture, with subsequent evaluation of the collected fractions purity by MCE. The necessary theoretical background is provided including both steering schemes and calculations of optimum oper... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3007409 Wed, 18 Nov 2009 00:00:00 +0100 3007409 http://www.medworm.com/index.php?rid=3007408&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900349 Microchip CE of proteins labeled either off- or on-chip with the "chameleon" CE dye 503 using poly(methyl methacrylate) microchips is presented. A simple dynamic coating using the cationic surfactant CTAB prevented nonspecific adsorption of protein and dye to the channel walls. The labeling reactions for both off- and on-chip labeling proceeded at room temperature without requiring heating steps. In off-chip labeling, a 9 ng/mL concentration detection limit for BSA, corresponding to a [sim]7 fg (100 zmol) mass detection limit, was obtained. In on-chip tagging, the free dye and protein were placed in different reservoirs of the microchip, and an extra incubation step was not needed. A 1 [mu]g/mL concentration detection limit for BSA, corresponding to a [sim]700 fg (10 amol) mass detection l... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=3007408 Wed, 18 Nov 2009 00:00:00 +0100 3007408 http://www.medworm.com/index.php?rid=2998947&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900400 This paper presents a novel simple micromixer based on stable water suspensions of magnetic nanoparticles (i.e. ferrofluids). The micromixer chip is built using standard microfabrication and simple soft lithography, and the design can be incorporated as a subsystem into any chemical microreactor or a miniaturized biological sensor. An electromagnet driven by an AC power source is used to induce transient interactive flows between a ferrofluid and Rhodamine B. The alternative magnetic field causes the ferrofluid to expand significantly and uniformly toward Rhodamine B, associated with a great number of extremely fine fingering structures on the interface in the upstream and downstream regions of the microchannel. These pronounced fingering patterns, which have not been observed by other act... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2998947 Tue, 17 Nov 2009 00:00:00 +0100 2998947 http://www.medworm.com/index.php?rid=2953889&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900456 Two types of monolithic silica capillary columns with an immobilized cellulose tris(3,5-dimethylphenylcarbamate) (CDMPC) selector were prepared for enantiomer separations in CEC. The monolithic columns were prepared by a sol-gel process in fused-silica capillaries. CDMPC was then either immobilized on a silica monolith through an intermolecular polycondensation of the cellulose derivative containing a triethoxysilyl group, or on a vinylized silica monolith through radical copolymerization of the cellulose derivative, which also contained a vinyl group. IR spectra confirmed the successful immobilization of CDMPC on both columns. Eleven chiral compounds were used to evaluate the enantioselectivity on both column types. Results indicated that the columns obtained via polycondensation had high... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2953889 Tue, 03 Nov 2009 00:00:00 +0100 2953889 http://www.medworm.com/index.php?rid=2953897&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200800638 In this article, a new type of microchip with filmy channels and a sample-injection fracture is introduced. Unlike commercial microchip, new microchip possessed filmy channel with width 2-3 mm. The effective cooling ability made filmy channel microchip restrain the generation of Joule heat even under electric field of 588 V/cm. Moreover, wider channel could be more easily modified to prevent the absorption of samples, load more samples and result in a higher sensitivity. Sample-injection fracture was first applied to match the filmy channel in microchip. Equipped with an amperometric detector, the characteristics of the newly designed filmy channel microchip had been studied and the results showed that it had good reproducibility, higher sensitivity and excellent separation ability. The mi... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2953897 Mon, 02 Nov 2009 00:00:00 +0100 2953897 http://www.medworm.com/index.php?rid=2953896&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900281 CE with tris(2,2[prime]-bipyridyl) ruthenium(II) (Ru(bpy)32+) electrochemiluminescence (ECL) detection for the quantitative determination of isocyanates was first reported. Hexamethylene diisocyanate (HDI) and hexyl isocyanate (HI) were used as the model analytes. Commercially available N,N-diethyl-N[prime]-methylethylenediamine was used as the derivatization reagent. It has both a secondary amine group and a tertiary amine group. The secondary amine group can quantitatively react with isocyanate group, and the tertiary amine group can react with Ru(bpy)32+ to produce strong ECL signal for sensitive detection. The derivatization reaction was almost instantaneous and is much faster than other reported derivative reactions using other derivative reagents. The urea formed was stable. Linear c... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2953896 Mon, 02 Nov 2009 00:00:00 +0100 2953896 http://www.medworm.com/index.php?rid=2953895&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900379 A silica based monolithic capillary column derivatized with O-9-(tert-butylcarbamoyl)quinidine was prepared for CEC enantiomer separation of chiral 2-aryloxypropionic acid herbicides including inter alia dichlorprop, mecoprop and fenoprop. The silica monolith had a relatively low surface coverage with chiral cationic selector moieties. Due to the low selector density retention factors were low as well, yet still enabling enantiomer separations of the target solutes. Both electrophoretically and chromatographically dominated migration and separation modes, respectively, could be established depending on the employed conditions. In the former mode, enantiomers migrated in front of the EOF marker, and faster separations and higher plate numbers could be achieved. In the latter mode, stronger ... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2953895 Mon, 02 Nov 2009 00:00:00 +0100 2953895 http://www.medworm.com/index.php?rid=2953894&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900434 A novel anionic surfactant bound monolithic stationary phase based on 11-acrylaminoundecanoic acid is designed for CEC. The monolith possessing bonded undecanoyl groups (hydrophobic sites) and carboxyl groups (weak cationic ion-exchange sites) were evaluated as a mixed-mode stationary phase in CEC for the separation of neutral and polar solutes. Using a multivariate D-optimal design the composition of the polymerization mixture was modeled and optimized with five alkylbenzenes and seven alkyl phenyl ketones as test solutes. The D-optimal design indicates a strong dependence of electrochromatographic parameters on the concentration of 11-acrylaminoundecanoic acid monomer and porogen (water) in the polymerization mixture. A difference of 6, 8 and 13% RSD between the predicted and the experim... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2953894 Mon, 02 Nov 2009 00:00:00 +0100 2953894 http://www.medworm.com/index.php?rid=2953893&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900288 Functionalized multiwalled carbon nanotubes (f-MWCNTs) can serve as the pseudostationary phase (PSP) for the capillary EKC separation of non-steroidal anti-inflammatory drugs (NSAIDs). To increase their hydrophilicity, we treated MWCNTs, with a sonochemical process in a concentrated nitric/sulfuric acid mixture. The oxidized MWCNTs were then characterized by FT-IR, transmission electron microscopy, and X-ray photoelectron spectroscopy. We evaluated the potential of the PSP and the effects of buffer composition, pH, addition of organic modifier, and injection temperature on the NSAID separation. The PSP created a network structure of [pi]-[pi] interactions, hydrophobic forces, hydrogen bonding, and electrostatic interactions to separate NSAIDs, providing a different separation mode from SDS... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2953893 Mon, 02 Nov 2009 00:00:00 +0100 2953893 http://www.medworm.com/index.php?rid=2953892&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900303 A dicationic ion-pairing reagent, N,N[prime]-dibutyl 1,1[prime]-pentylenedipyrrolidinium, was used to form complexes with singly charged anions for their subsequent analysis by CE-ESI-MS in positive ion mode. This methodology offers the advantages of greater versatility and sensitivity relative to direct detection of the anions in negative ion mode, and it can be realized by a number of possible complexation strategies, including pre-column, on-column, and post-column modes. Four model anions, perfluorooctanoate, benzenesulfonate (BZSN), monochloroacetate (MCA), and trifluoromethanesulfonimide were amenable to complexation with the dicationic reagent, yielding singly charged cations with greater m/z. By optimizing various parameters, including the CE separation buffer composition and pH, t... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2953892 Mon, 02 Nov 2009 00:00:00 +0100 2953892 http://www.medworm.com/index.php?rid=2953891&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900386 In this study, a series of novel polymeric monolithic columns prepared by single-step in situ copolymerization of 1-octadecene (OD), divinylbenzene (DVB) and/or styrene (S), were developed as separation columns for the sulfonamide analyses. On the CEC method, the composition of monomer mixtures (i.e. the ratio of S versus OD), content of charge-bearing monomer (vinylbenzyl trimethylammonium chloride) and volume fraction ratio of ACN in the mobile phase, was found to be the predominant influences for sulfonamide separation. Furthermore, an online sample concentration step, field-amplified sample injection, was used to enhance the detection sensitivity of sulfonamides. Sample matrix's pH had a significant effect on the sulfonamide sensitivity. For the eight sulfonamides, the proposed poly(DV... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2953891 Mon, 02 Nov 2009 00:00:00 +0100 2953891 http://www.medworm.com/index.php?rid=2953890&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900395 A new simple and fast noncovalent coating method based on poly(1-vinylpyrrolidone-co-2-dimethylaminoethyl methacrylate) copolymer was developed for CE. Merely 2 min flushing of the capillary with the poly(1-vinylpyrrolidone-co-2-dimethylaminoethyl methacrylate) copolymer was required. The copolymer is adsorbed onto the fused-silica surface by hydrogen bonding and electrostatic interactions. EOF was almost totally suppressed over a wide pH range. The coating conditions (flushing time, copolymer concentration, and the concentration and pH of background electrolyte solution) and the stability of the coating were optimized, and the coated capillary was successfully applied to the fast separation of four basic proteins: lysozyme, cytochrome c, ribonuclease A, and [alpha]-chymotrypsinogen A. Sep... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2953890 Mon, 02 Nov 2009 00:00:00 +0100 2953890 http://www.medworm.com/index.php?rid=2938537&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900245 In this study, stable collagen and collagen-decorin coatings were prepared on the inner surfaces of fused silica CEC capillaries, enabling study of the interactions between collagen and selected peptide fragments of apolipoprotein B-100 (apoB-100), the main protein of low-density lipoprotein (LDL) particles. Interactions of positive, neutral, and negative peptide fragments of apoB-100 were elucidated. The selected positive peptide contains the sequence involved in the interaction of LDL with LDL receptor and proteoglycans. Retention factors of the peptides that were determined without any voltage, by exploiting pressure, gave numerical information about interactions with the collagen coatings. The inclusion of decorin in the coatings confirmed the importance of glycosaminoglycans in mediat... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2938537 Thu, 29 Oct 2009 00:00:00 +0100 2938537 http://www.medworm.com/index.php?rid=2938543&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200800841 An open-tubular (OT) CEC column was designed to anchor ionizable succinate-functionalized ligands onto a silica hydride-based stationary phase through surface etching, silanization, and hydrosilation reactions beginning from a bare fused-silica tube. The modified columns that were produced in each step were monitored by analysis of the effect of performance of EOF on the changes of pH values, concentrations, and the amount of ACN added in the running buffers. By tracking the EOF patterns between columns, the author determined that the surface composition of the final product column was a combination of silanols, silica hydrides, and succinate ligands. Furthermore, lower loading volumes of the succinate ligands prepared for the hydrosilation reaction served to complete the mixed-mode OT-CEC... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2938543 Wed, 28 Oct 2009 00:00:00 +0100 2938543 http://www.medworm.com/index.php?rid=2938542&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900057 Cellulose dimethylphenylcarbamate (CDMPC)-immobilized zirconia (CDMPCZ) was used as a chiral stationary phase for enantioseparation of a set of nine racemic compounds in reversed-phase CEC. Influences of the type and composition of organic modifier and the applied voltage on enantioseparation were examined. Separation data on CDMPCZ were also compared with those on CDMPC-immobilized silica (CDMPCS). Enantiomers of the analytes investigated are well separated in ACN/phosphate buffer mobile phases. Better enantioselectivity and resolution were obtained with ACN than MeOH as the organic modifier. Retention was longer but better enantioselectivity and resolution were obtained on CDMPCZ than CDMPCS. (Source: Electrophoresis) Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2938542 Wed, 28 Oct 2009 00:00:00 +0100 2938542 http://www.medworm.com/index.php?rid=2938541&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900060 A CE assay for the simultaneous determination of the impurities of levodopa listed in the European Pharmacopoeia including the (R)-enantiomer was developed and validated. The analysis was performed in a fused-silica capillary employing sulfated [beta]-cyclodextrin as chiral selector at an applied voltage of 20 kV and a temperature of 18°C. The optimized background electrolyte consisted of 0.1 M sodium phosphate buffer, pH 2.0, containing 6 mg/mL sulfated [beta]-cyclodextrin. L-phenylalanine was used as the internal standard. The assay was validated in the range of 0.1-1.0% for the impurities at a concentration of levodopa of 2 mg/mL. The effect of different batches of sulfated [beta]-cyclodextrin was investigated using levodopa and L-tyrosine as critical pair. The method was applied to de... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2938541 Wed, 28 Oct 2009 00:00:00 +0100 2938541 http://www.medworm.com/index.php?rid=2938540&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900169 This article describes a single MEKC method that can simultaneously determine all the listed compounds with acceptable LOD and LOQ. All the analytes were successfully separated by MEKC using running buffer containing 40 mM SDS, 20 mM sodium phosphate, and 20 mM sodium borate at pH 9.0. The MEKC method was compared to the corresponding CZE method using the same running buffer containing no SDS. The effect of SDS concentration on separation, the pH of the running buffer, and the detection wavelength were studied and optimal MEKC conditions were established. Good linearity was obtained with correlation coefficients of more than 0.99 for all analytes. Specificity, accuracy, and precision were also evaluated. The recovery was in the range of 89-112%. The precision results were in the range of 1... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2938540 Wed, 28 Oct 2009 00:00:00 +0100 2938540 http://www.medworm.com/index.php?rid=2938539&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900216 A CE method is described for the enantioselective analysis of propranolol (Prop) and 4-hydroxypropranolol (4-OH-Prop) in liquid Czapek medium with application in the study of the enantioselective biotransformation of Prop by endophytic fungi. The electrophoretic conditions previously optimized were as follows: an uncoated fused-silica capillary, 4% w/v carboxymethyl-[beta]-CD in 25 mmol/L triethylamine/phosphoric acid (H3PO4) buffer at pH 9 as running electrolyte and 17 kV of voltage. UV detection was carried out at 208 nm. Liquid-liquid extraction using diethyl ether: ethyl acetate (1:1 v/v) as extractor solvent was employed for sample preparation. The calibration curves were linear over the concentration range of 0.25-10.0 [mu]g/mL for each 4-OH-Prop enantiomer and 0.10-10.0 [mu]g/mL for... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2938539 Wed, 28 Oct 2009 00:00:00 +0100 2938539 http://www.medworm.com/index.php?rid=2938538&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900230 Identification of microbial contamination by CE has interested many researchers mainly because of the high speed of CE analysis. However, the CE separation of such big structures brings a lot of questions mainly about the behavior of microorganisms and about the mechanism of separation. In this work, we constructed a simple apparatus where a microscope was used as one detector and a UV detector was used as the second one and we made the comparison of three typical setups for CE of microorganisms. Saccharomyces cerevisiae was chosen as a model microorganism and was analyzed in bare fused-silica capillaries, covalently modified capillaries and dynamically modified capillaries by poly(ethylene oxide) or CTAB. Results showed that the use of CE instrument directly connected with a microscope co... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2938538 Wed, 28 Oct 2009 00:00:00 +0100 2938538 http://www.medworm.com/index.php?rid=2915430&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900299 Detection of microbial contamination is of critical importance in the medical and the food industry. Rapid tests for the absence or presence of viable microorganisms are in urgent demand. CE is a modern analytical technique that can be adapted for rapid screening of microbial contamination. However, the small dimensions of capillaries allow the introduction of only a small fraction of the sample, which can be problematic when examining large samples. In this article, we examine the possibilities of introducing larger sample volumes using capillaries with greater id together with different stacking techniques. The use of 0.32 mm id capillary and the injection of 60% of the capillary volume led to approximately 120-fold improvement of the injected sample volume over the classical injection 5... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2915430 Tue, 20 Oct 2009 23:00:00 +0100 2915430 http://www.medworm.com/index.php?rid=2915429&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900416 In this study, novel phosphonium-based mono- and dicationic reagents (originally synthesized as ionic liquids) were evaluated as additives to the BGE for the separation of inorganic and small organic anions. The effects of these reagents on the EOF and their interactions with anionic analytes were compared. The effects of the additive's structure and concentration as well as the separation buffer pH have been studied. Propane-1,3-bis(tripropylphosphonium) fluoride proved to be the most effective additive, as it suppressed the EOF in the system and enabled remarkable manipulation of separation selectivity. A method for fast, reliable, and efficient separation of six inorganic and seven organic anions within 7 min time was developed using propane-1,3-bis(tripropylphosphonium) fluoride as an ... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2915429 Tue, 20 Oct 2009 23:00:00 +0100 2915429 http://www.medworm.com/index.php?rid=2875133&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900038 Lauryl methacrylate (LMA)-ester based monolithic columns photo-polymerized using lauroyl peroxide (LPO) as initiator were prepared, and their morphological and CEC properties were studied. The composition of the polymerization mixture (i.e. ratios of monomers/porogenic solvents, 1,4-butanediol/1-propanol and LMA/crosslinker) was optimized. The morphological and chromatographic properties of LMA columns were evaluated by means of SEM pictures and van Deemter plots of PAHs, respectively. The polymerization mixture selected as optimal provided a fast separation of a mixture of PAHs with excellent efficiencies (minimum plate heights of 8.9-11.1 [mu]m). Satisfactory column-to-column (RSD (Source: Electrophoresis) Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2875133 Wed, 07 Oct 2009 23:00:00 +0100 2875133 http://www.medworm.com/index.php?rid=2875132&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900384 The aim of the present study was the investigation of the effect of urea on analyte complexation in CD-mediated separations of peptide enantiomers by CE in the pH range of about 2-5. pH-independent complexation and mobility parameters in the absence and presence of 2 M urea were obtained by three-dimensional, non-linear curve fitting of the effective analyte mobility as a function of pH and heptakis-(2,6-di-O-methyl)-[beta]-CD concentration. Urea led to decreased binding strength of the CD towards the protonated and neutral analyte enantiomers as well as to decreased mobilities of the free analytes. In contrast, mobilities of the fully protonated enantiomer-CD complexes as well as the pKa values of the free and complexed analytes increased. The effect of urea on separation efficiency varie... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2875132 Wed, 07 Oct 2009 23:00:00 +0100 2875132 http://www.medworm.com/index.php?rid=2871160&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200800719 A glycosphingolipid analogue (12-azidododecyl [beta]-lactoside) as a saccharide primer has been shown to be useful for the synthesis of oligosaccharide libraries by mammalian cells. In the present study, CE-ESI-MS was employed to elucidate the structure of glycosphingolipid analogues derived from 12-azidododecyl [beta]-lactoside (Lac-C12N3) by mammalian cells. MDCK cells and COLO201 cells were cultured with Lac-C12N3, and the glycosylated products secreted into the medium were collected and separated into acidic and neutral products by column chromatography. The acidic products could be directly analyzed by CE-ESI-MS, while the neutral products were converted to anionic derivatives via a reaction with propiolic acid. With this method, it was possible to analyze both acidic and neutral prod... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2871160 Tue, 06 Oct 2009 23:00:00 +0100 2871160 http://www.medworm.com/index.php?rid=2868454&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900079 This paper presents the development and experimental analysis of a dielectrophoresis (DEP) system, which is used for the manipulation and separation of microparticles in liquid flow. The system is composed of arrays of microelectrodes integrated to a microchannel. Novel curved microelectrodes are symmetrically placed with respect to the centre of the microchannel with a minimum gap of 40 [mu]m. Computational fluid dynamics method is utilised to characterise the DEP field and predict the dynamics of particles. The performance of the system is assessed with microspheres of 1, 5 and 12 [mu]m diameters. When a high-frequency potential is applied to microelectrodes a spatially varying electric field is induced in the microchannel, which creates the DEP force. Negative-DEP behaviour is observed ... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2868454 Mon, 05 Oct 2009 23:00:00 +0100 2868454 http://www.medworm.com/index.php?rid=2868453&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900093 The diastereoisomeric separation of peptidomimetics of hexarelin, a strong growth hormone secretagogue, in CE has been studied. Highly sulfated-[gamma]-CD was found to be an appropriate selector for the separation of the stereoisomers. However, non-repeatable analyses were obtained on bare fused silica capillary due to the progressive adsorption of the analytes on the capillary wall. Two types of polyelectrolyte coating agents were tested to prevent this phenomenon. Coating with neutral polyethylene oxide was found to be efficient but resulted in a very long analysis time (about 40 min). Coating with cationic poly(diallyldimethylammonium) chloride was found both to prevent analyte adsorption, reduce analysis time and alter separation selectivity. EOF measurement revealed that the highly su... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2868453 Mon, 05 Oct 2009 23:00:00 +0100 2868453 http://www.medworm.com/index.php?rid=2868452&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900340 A novel method capable of differentiating and concentrating small molecules in bulk solution termed "electrophoretic exclusion" is described and experimentally investigated. In this technique, the hydrodynamic flow of the system is countered by the electrophoretic velocity to prevent a species from entering into the channel. The separation can be controlled by changing the flow rate or applied electric field in order to exclude certain species selectively while allowing others to pass through the capillary. Proof of principle studies employed a flow injection regime of the method and examined the exclusion of Methyl Violet dye in the presence of a neutral species. Methyl Violet was concentrated almost 40 times the background concentration in 30 s using 6 kV. Additionally, a threshold volta... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2868452 Mon, 05 Oct 2009 23:00:00 +0100 2868452 http://www.medworm.com/index.php?rid=2868451&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900197 African mitochondrial DNA (mtDNA) haplogroups are divided into seven macro-haplogroups (L0[prime]1[prime]2[prime]3[prime]4[prime]5[prime]6), while the rest of the world's lineages are classified as subgroups of macro-haplogroups M, N and R. The most common approach to characterizing mtDNA variation is the sequencing of hypervariable segments I and II of the non-coding control region of the molecule. Given the higher mutation rate within the control region compared with the coding regions of the molecule, recurrent mutations in the former can sometimes hide possible phylogenetic structure. The incorporation of haplogroup-defining coding region mutations has helped in overcoming this limitation. By judiciously selecting 14 coding region SNPs and incorporating them into a multiplex minisequen... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2868451 Mon, 05 Oct 2009 23:00:00 +0100 2868451 http://www.medworm.com/index.php?rid=2854939&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900323 DNA computing is a new computation form based on DNA biochemical reactions, which is mainly composed of sticker and splicing computation models. In this work, a microfluidic chip-based approach was established for splicing model-based DNA computing. A finite automaton with two input symbols (a, b) and three states (S0, S1, and S2) was applied in the pattern recognition for isosceles triangles. The DNA computation processes of automaton were realized through DNA digestion, ligation, DNA separation, and detection on the microfluidic chip. The established approach is efficient, controllable, and easy to integrate, which paves the way for the building of complete biomolecular computers in the future. (Source: Electrophoresis) Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2854939 Wed, 30 Sep 2009 23:00:00 +0100 2854939 http://www.medworm.com/index.php?rid=2854938&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900191 The process of 0-4% PEG precipitation of high-molecular-mass proteins (around and above 1×103 kDa) in human plasma was analyzed by non-denaturing micro 2-DE employing agarose IEF gels in the first dimension, and by MALDI-MS PMF. The PEG 0-2% precipitate could be mostly re-dissolved (fraction PS2%), but some part remained as precipitate (fraction PP2%). Non-denaturing 2-DE followed by MALDI-MS PMF showed that PS2% contained fibrinogen (Fb), fibronectin (FN), and their oligomers as the major components, and von Willebrand factor and coagulation factor XIII as the minor components. PP2% was directly subjected to MALDI-MS PMF and FN and Fb were assigned, suggesting it was formed by co-precipitation of the two proteins. The PEG 2-4% precipitate could be totally dissolved, but after freezing an... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2854938 Wed, 30 Sep 2009 23:00:00 +0100 2854938 http://www.medworm.com/index.php?rid=2854937&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900018 In this paper, a novel highly cross-linked porous monolithic stationary phase having a long alkyl chain ligand (C16) was introduced and evaluated in CEC. The monolithic stationary phase was prepared by in situ copolymerization of 1-hexadecene, trimethylolpropane trimethacrylate, and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) in the presence of ternary porogenic solvent (cyclohexanol/1,4-butanediol/water). In preparing monoliths, the ternary cross-linker trimethylolpropane trimethacrylate was usually applied to preparing molecularly imprinted polymers or molecularly imprinted solid-phase extraction, instead of binary cross-linker ethylene dimethacrylate. 1-Hexadecene was introduced to provide the non-polar sites (C16) for chromatographic retention, while AMPS was used to generate t... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2854937 Wed, 30 Sep 2009 23:00:00 +0100 2854937 http://www.medworm.com/index.php?rid=2854936&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900195 A new method for high-sensitive determination of glutamate was developed and evaluated based on CE by using dual-enzyme co-immobilized capillary microreactor combined with substrate recycling. The capillary microreactor was prepared by covalently co-immobilizing glutamate dehydrogenase (GDH) and glutamic pyruvic transaminase (GPT) on the inner surface of a capillary and was characterized by SEM, ultraviolet-visible spectroscopy, and fluorescence spectroscopy. The GDH-GPT co-immobilized capillary microreactor showed great stability and reproducibility. The apparent Km for glutamate with GDH-GPT coupled reaction was determined to be 0.61±0.06 mM but 2.56±0.24 mM when only GDH was immobilized. Glutamate determination was based on on-column monitoring UV absorption at 340 nm of the reaction ... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2854936 Wed, 30 Sep 2009 23:00:00 +0100 2854936 http://www.medworm.com/index.php?rid=2833991&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900259 A recently developed proteomic strategy, the "GG-azide"-labeling approach, is described for the detection and proteomic analysis of geranylgeranylated proteins. This approach involves metabolic incorporation of a synthetic azido-geranylgeranyl analog and chemoselective derivatization of azido-geranylgeranyl-modified proteins by the "click" chemistry, using a tetramethylrhodamine-alkyne. The resulting conjugated proteins can be separated by 1-D or 2-D and pH fractionation, and detected by fluorescence imaging. This method is compatible with downstream LC-MS/MS analysis. Proteomic analysis of conjugated proteins by this approach identified several known geranylgeranylated proteins as well as Rap2c, a novel member of the Ras family. Furthermore, prenylation of progerin in mouse embryonic fibr... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2833991 Fri, 25 Sep 2009 23:00:00 +0100 2833991 http://www.medworm.com/index.php?rid=2833995&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900142 We describe microchip-based phosphate-affinity electrophoresis ([mu]PAE) for separation of peptides aimed at determination of kinase activity. The [mu]PAE exploits two recently published technologies: autonomous sample injection for PDMS microchips and a phosphate-specific affinity ligand, Phos-tag. We prepared a fluorescently labeled substrate peptide, specific to human c-Src, and its phosphorylated form. We synthesized a Phos-tag-poly(dimethylacrylamide) conjugate. The conjugate and the sample solutions were autonomously injected into a PDMS-glass hybrid microchip. The two solutions were contacted together in the microchannel. When the peptides were electrophoresed into the Phos-tag-poly(dimethylacrylamide) region, the phosphorylated peptide was specifically trapped, and separated from t... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2833995 Thu, 24 Sep 2009 23:00:00 +0100 2833995 http://www.medworm.com/index.php?rid=2833994&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900271 A microfluidic pump based on electroosmosis of the second kind was designed and fabricated. Experimental results using DC and AC voltages showed a close to second-order relationship between flow and voltage, in good agreement with theory. The experimental flow rates were considerably lower than the predicted maximum for the micropumps, which can be attributed to the hydrodynamic resistance of the channel network. This also indicates that higher flow velocities are obtainable for modified pump designs. (Source: Electrophoresis) Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2833994 Thu, 24 Sep 2009 23:00:00 +0100 2833994 http://www.medworm.com/index.php?rid=2833993&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900114 Native electrophoresis is a powerful tool for the separation of intact protein complexes. By incubating such gels in a suitable reaction solution, specific enzyme activities can be screened comprehensively. The recent standard procedure for determination of ATP hydrolysis activity in blue or clear native gels is based on formation of a lead phosphate precipitate. The resulting white bands are challenging for detection and documentation of low activities. For the analysis of photosynthetic ATP synthases, the method has to be adapted to deregulate the inhibition of latent ATPase functions. Therefore, we introduced an incubation of gels in detergent solution, whereby taurodeoxycholate turned out to be the most efficient activator. In order to detect low ATPase activities, a short additional i... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2833993 Thu, 24 Sep 2009 23:00:00 +0100 2833993 http://www.medworm.com/index.php?rid=2833992&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900261 Ca2+ complexation by both sulfate and selenate ligands was studied by CE. The species were observed to give a unique retention peak as a result of a fast equilibrium between the free ions and the complexes. The change in the corresponding retention time was interpreted with respect to the equilibrium constant of the complexation reaction. The results confirmed the formation of CaSO4(aq) and CaSeO4(aq) under our experimental conditions. The formation data were derived from the series of measurements carried out at about 15, 25, 35, 45 and 55°C in 0.1 mol/L NaNO3 ionic strength solutions, and in 0.5 and 1.0 mol/L NaNO3 ionic strength solutions at 25°C. Using a constant enthalpy of reaction enabled to fit all the experimental data in a 0.1 mol/L medium, leading to the thermodynamic paramete... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2833992 Thu, 24 Sep 2009 23:00:00 +0100 2833992 http://www.medworm.com/index.php?rid=2812119&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900070 In-gel digestion of gel-separated proteins is a major route to assist in proteomics-based biological discovery, which, however, is often embarrassed by its inherent limitations such as the low digestion efficiency and the low recovery of proteolytic peptides. For overcoming these limitations, many efforts have been directed at developing alternative methods to avoid the in-digestion. Here, we present a new method for efficient protein digestion and tryptic peptide recovery, which involved electroblotting gel-separated proteins onto a PVDF membrane, excising the PVDF bands containing protein of interest, and dissolving the bands with pure DMF ([ge]99.8%). Before tryptic digestion, NH4HCO3 buffer was added to moderately adjust the DMF concentration (to 40%) in order for trypsin to exert its ... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2812119 Thu, 17 Sep 2009 23:00:00 +0100 2812119 http://www.medworm.com/index.php?rid=2812118&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900270 Proteomic methods were used to identify the levels of impurities in three commercial plasma-derived clotting factor VIII-von Willebrand factor (FVIII/VWF) concentrates. In all three concentrates, significant amounts of other plasma proteins were found. In Octanate and Haemoctin, two concentrates developed in the 1990s, the major impurities identified were inter-[alpha] inhibitor proteins, fibrinogen and fibronectin. These two concentrates were also found to contain additional components such as clotting factor II (prothrombin) that are known activators of FVIII. In Wilate, a recently developed FVIII/VWF concentrate, the amount of these impurities was significantly reduced. Batch-to-batch variations and differences between three investigated products were detected using iTRAQ, an isotope la... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2812118 Thu, 17 Sep 2009 23:00:00 +0100 2812118 http://www.medworm.com/index.php?rid=2812117&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900063 Chemometric techniques usually employed in purity assessment and resolution of multicomponent peaks have been applied to analytical data from complex biological samples obtained with CE-DAD. In the assessment of the purity of the electrophoretic peaks, the orthogonal projection approach, the orthogonal projection approach with Durbin-Watson criterion, and the simple-to-use interactive self-modeling mixture analysis method have been employed. Multivariate curve resolution with alternating least squares has been successfully implemented to resolve co-migrating peaks of metabolites in CE-DAD and to recover qualitative and quantitative information about co-migrating components of urine extract. The main challenge consisted of developing high-quality multivariate curve resolution with alternati... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2812117 Thu, 17 Sep 2009 23:00:00 +0100 2812117 http://www.medworm.com/index.php?rid=2812116&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900185 The utilization of CE for monitoring bacteria-phage interaction was investigated in this study. Streptococcus thermophilus and Lactobacillus bulgaricus strains and their phages were used as model bacteria and phages for the purpose of validation in this study. CE with heterogeneous polymer polyethylene oxide was utilized for the separation of intact bacteria and investigation of phage-bacteria interaction. An intact phage detection was carried out with CZE by adding SDS in the running buffer. Calibration graphs of bacteria and phages were obtained with R2 values of 0.963 and 0.937, respectively. S. thermophilus strain was infected with its virulent phage B3-X18 for investigation of phage-bacteria interaction. It was observed in capillary electropherogram that the culture was lysed dependin... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2812116 Thu, 17 Sep 2009 23:00:00 +0100 2812116 http://www.medworm.com/index.php?rid=2812115&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900255 We evaluated the mesh size and homogeneity of polymer network by dynamic light scattering and discussed the relationship between the physical properties of polymer network and the protein separation behavior by capillary polymer electrophoresis. We compared three kinds of sieving polymers in solutions with a wide range of molecular weights and concentrations: polyacrylamide and polyethylene oxide as flexible polymers, and hydroxyethyl cellulose as a semiflexible polymer. We found that the mobility of protein was dominated primarily by the mesh size [xi], irrespective of the type of sieving polymers, and the peak spacing between protein peaks increased drastically in the range of [xi] (Source: Electrophoresis) Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2812115 Thu, 17 Sep 2009 23:00:00 +0100 2812115 http://www.medworm.com/index.php?rid=2799852&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900037 In this paper, titanium dioxide nanoparticles (TiO2 NPs) were employed to construct a functional film on PDMS microfluidic channel surface, which was formed by sequentially immobilizing poly(diallyldimethylammonium chloride) and TiO2 NPs on PDMS surface by layer-by-layer assembly technique. The modified PDMS microchip exhibited a decreased and stable EOF, which was favorable for the separation of biomolecules with similar migration times. Arginine, phenylalanine, serine and threonine were used as model analytes to evaluate the performance of the modified microchip. The four amino acids were efficiently separated within 100 s in a 3.7 cm long separation channel and successfully detected on the carbon fiber electrode in conjunction with in-channel indirect amperometry. Resolutions and theore... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2799852 Mon, 14 Sep 2009 23:00:00 +0100 2799852 http://www.medworm.com/index.php?rid=2799851&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900075 The design of new electrochemical devices integrating carbon nanotube sensors and their adaptation to commercial CE equipments are described. One of these designs was made for using commercial screen-printed electrodes, whereas the second was projected for coupling commercial glassy carbon electrodes. The electrochemical characterization of these devices revealed that their hydrodynamic behaviour is strongly influenced by the electrode modification with multi-wall carbon nanotubes that provided faster and/or more sensitive signals. The analytical applicability of these devices was illustrated for the CZE separation of chlorinated phenols and the MEKC separation of endocrine disruptors, where the use of carbon nanotube sensors has proved to be advantageous when compared with unmodified ones... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2799851 Mon, 14 Sep 2009 23:00:00 +0100 2799851 http://www.medworm.com/index.php?rid=2799850&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900080 An all-in-one version of a capacitively coupled contactless conductivity detector is introduced. The absence of moving parts (potentiometers and connectors) makes it compact (6.5 cm3) and robust. A local oscillator, working at 1.1 MHz, was optimized to use capillaries of id from 20 to 100 [mu]m. Low noise circuitry and a high-resolution analog-to-digital converter (ADC) (21 bits effective) grant good sensitivities for capillaries and background electrolytes currently used in capillary electrophoresis. The fixed frequency and amplitude of the signal generator is a drawback that is compensated by the steady calibration curves for conductivity. Another advantage is the possibility of determining the inner diameter of a capillary by reading the ADC when air and subsequently water flow through ... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2799850 Mon, 14 Sep 2009 23:00:00 +0100 2799850 http://www.medworm.com/index.php?rid=2799849&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900184 The hydrolysis of acetylcholine and acetylthiocholine as catalyzed by the enzyme acetylcholinesterase was monitored by CE with contactless conductivity detection by determining the acetate produced in the reaction. This approach eliminates the need for a color forming derivatization procedure. The effects of the three inhibitors galanthamine, hyperzine A and paraoxon on the enzyme kinetics could also be investigated by the new procedure and the IC50 values were determined. The contactless conductivity detection was also found to be compatible with the electrophoretically mediated microanalyis approach, in which the enzymatic reaction is carried out directly inside the capillary prior to separation and quantification. (Source: Electrophoresis) Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2799849 Mon, 14 Sep 2009 23:00:00 +0100 2799849 http://www.medworm.com/index.php?rid=2799848&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900187 CE with contactless conductivity detection has been used to determine the glycine neurotransmitter in periaqueductal gray matter (PAG) of rats. The LOD for glycine has been decreased to a value of 0.2 [mu]M by adding 75% v/v of ACN to the samples and increasing the sample zone introduced to a value of 20% of the overall capillary length. The repeatabilities of the analyte migration times and the zone areas amount to 2.1 and 2.7%, respectively. The optimized CE/contactless conductivity detection method makes it possible to determine the micromolar concentrations of glycine in PAG microdialyzates without the necessity of sample derivatization. It follows from a pharmacological study that a local inflammation initiated by an application of carrageenan increased the glycine concentration in th... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2799848 Mon, 14 Sep 2009 23:00:00 +0100 2799848 http://www.medworm.com/index.php?rid=2777764&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900234 Although it has been shown that microchip electrophoresis (MCE) with electrochemical detection can be used to separate and detect electroactive species, there is a need to increase the separation performance of these devices so that complex mixtures can be routinely analyzed. Previous work in the MCE has demonstrated that increasing the separation channel length leads to an increase in resolution between closely eluting analytes. This paper details the use of lengthened serpentine microchannels for MCE and electrochemical detection where a palladium decoupler is used to ground the separation voltage so that the working electrodes remain in the fluidic network. In this work, palladium electrodepositions were used to increase the decoupler surface area and more efficiently dissipate hydrogen... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2777764 Mon, 07 Sep 2009 23:00:00 +0100 2777764 http://www.medworm.com/index.php?rid=2777763&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900238 A new strategy based on the fast separation of the fingerprint markers of Vanilla planifolia extracts and vanilla-related samples on microfluidic-electrochemistry chip is proposed. This methodology allowed the detection of all required markers for confirmation of common frauds in this field. The elution order was strategically connected with sequential sample screening and analyte confirmation steps, where first ethyl vanillin was detected to distinguish natural from adultered samples; second, vanillin as prominent marker in V. planifolia, but frequently added in its synthetic form; and third, the final detection of the fingerprint markers (p-hydroxybenzaldehyde, vanillic acid, and p-hydroxybenzoic acid) of V. planifolia with confirmation purposes. The reliability of the proposed methodolo... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2777763 Mon, 07 Sep 2009 23:00:00 +0100 2777763 http://www.medworm.com/index.php?rid=2777762&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900368 We present the rapid prototyping of electrochemical sensor arrays integrated to microfluidics towards the fabrication of integrated microsystems prototypes for point-of-care diagnostics. Rapid prototyping of microfluidics was realised by high-precision milling of polycarbonate sheets, which offers flexibility and rapid turnover of the desired designs. On the other hand, the electrochemical sensor arrays were fabricated using standard photolithographic and metal (gold and silver) deposition technology in order to realise three-electrode cells comprising gold counter and working electrodes as well as silver reference electrode. The integration of fluidic chips and electrode arrays was realised via a laser-machined double-sided adhesive gasket that allowed creating the microchannels necessary... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2777762 Mon, 07 Sep 2009 23:00:00 +0100 2777762 http://www.medworm.com/index.php?rid=2777761&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900324 A systematic comparison of UV and electrochemical detection (ED) in conjunction with NACE has been performed for capillaries with different ids ranging from 75 down to 2 [mu]m. Ferrocene, (ferrocenylmethyl)trimethylammonium acetate, atropine and scopolamine served as model analytes. All studies were done using an ACN-based nonaqueous electrophoresis buffer. For the comparison of detection performance, particular attention was paid to the absolute and relative LODs for decreasing capillary dimensions. In case of UV detection, a significant increase in relative LODs was typically observed for capillaries smaller than 25 [mu]m in diameter, while the absolute LODs remained nearly constant over a wide range of capillary dimensions. In contrast, ED showed some increase in relative LODs for capil... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2777761 Mon, 07 Sep 2009 23:00:00 +0100 2777761 http://www.medworm.com/index.php?rid=2761236&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900083 In this report we are employing a paired gold junction grown by electro-deposition to ca. 5 [mu]m gap size with the N,N-diethyl-N[prime],N[prime]-didodecyl-phenylene-diamine water immiscible redox liquid immobilized into the gap to demonstrate simultaneous perchlorate anion uptake and expulsion. The effects of redox liquid volume and scan rate on the magnitude of currents and two mechanistic pathways for ion transport are discussed in the context of micro-electrophoretic processes. (Source: Electrophoresis) Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2761236 Wed, 02 Sep 2009 23:00:00 +0100 2761236 http://www.medworm.com/index.php?rid=2761252&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200800845 We demonstrate here that the electrode kinetics of an electrochemical detector contributes greatly to the resolution of the analyte bands in microchip electrophoresis systems with amperometric detection. The separation performance in terms of resolution and theoretical plate number can be improved and tailored by selecting or modifying the working electrode and/or by controlling the detection potential. Such improvements in the separation performance reflect the influence of the heterogeneous electron-transfer rate of electroactive analytes upon the post-channel band broadening, as illustrated for catechol and hydrazine compounds. The electrode kinetics thus has a profound effect not only on the sensitivity of electrochemical detectors but on the separation efficiency and the overall perfo... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2761252 Tue, 01 Sep 2009 23:00:00 +0100 2761252 http://www.medworm.com/index.php?rid=2761251&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900008 The different approaches for constructing nanomaterial-based detectors for conventional CE and microchip electrophoresis are described in this review. They include three main types of nanomaterials, including carbon nanotubes, nanoparticles, and nanorods in various designs. The fundamental reasons for the enhanced detection performance of nanomaterial-based detectors, such as higher sensitivity, improved limits of detection, and higher peak capacity, are discussed in detail. Various applications for biomedical, food, and environmental analyses are reviewed. (Source: Electrophoresis) Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2761251 Tue, 01 Sep 2009 23:00:00 +0100 2761251 http://www.medworm.com/index.php?rid=2761245&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200800649 A simple, rapid, reproducible and sensitive method based on CE with electrochemical detector was developed for the simultaneous determination of five thyreostatics including 2-thiouracil (TU), 6-methyl-2-thiouracil (MTU), 6-propyl-2-thiouracil (PTU), 6-phenyl-2-thiouracil (PhTU) and methimazole (TAP) in animal feeds. A home-made wall-jet electrochemical detector with a 300 [mu]m diameter platinum-disk-working electrode was equipped at the end of separation capillary and used to detect oxidation currents of these thyreostatics. Under the optimum experimental conditions, TU, MTU, PTU, PhTU and TAP could be well separated within 15 min at the separation voltage of 16 kV in 20 mmol/L sodium borate buffer (pH 9.2). The detection limits (S/N=3) of the five thyreostatics in animal feeds were foun... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2761245 Tue, 01 Sep 2009 23:00:00 +0100 2761245 http://www.medworm.com/index.php?rid=2761244&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900019 In this report, a novel carbon nanotube/poly(ethylene-co-vinyl acetate) (CNT/EVA) composite electrode was developed for the amperometric detection in CE. The composite electrode was fabricated by packing a mixture of CNTs and melted EVA in a piece of fused-silica capillary under heat. It was coupled with CE for the separation and detection of esculin and esculetin in Cortex Fraxini, a traditional Chinese medicine, to demonstrate its feasibility and performance. Esculin and esculetin have been well separated within 9 min in a 40 cm long capillary at a separation voltage of 12 kV using a 50 mM borate buffer (pH 9.2). The new CNT-based CE detector offered significantly lower detection potentials, yielded enhanced S/N characteristics, and exhibited high resistance to surface fouling and enhanc... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2761244 Tue, 01 Sep 2009 23:00:00 +0100 2761244 http://www.medworm.com/index.php?rid=2761242&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900020 A novel method to detect [beta]-antagonists in rat blood was developed by combining heart-cutting 2-D CE in a single capillary with on-column electrochemical (EC) detection. The blood sample was purified in first dimension by non-micellar CZE separation. Then only a desirable fraction of the first dimension separation was transferred into the second dimension of the capillary by pressure. Finally, the purified sample was separated by MEKC. On-line dual concentration method, field amplified sample stacking and sweeping, was employed to accumulate the purified components that effectively counteracted the sample zone diffusion during the mobilization pressure step. A field decoupler joint and an EC detection cell were employed for on-column EC detection. After optimizing the analytical condit... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2761242 Tue, 01 Sep 2009 23:00:00 +0100 2761242 http://www.medworm.com/index.php?rid=2761240&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900285 In this research, ion transfer across the interface between two immiscible electrolyte solutions (ITIES) was used as a method of detection in a CE separation system. This method allows for the electrochemical detection of ionic analytes that cannot be easily oxidized or reduced. Method development revealed that the optimal separation conditions for three model ions (tetraethylammonium, tetrabutylammonium, and benzensulfonate) were found to be 5 mM sodium tetraborate buffer pH 9.2 with a separation voltage of 20 kV using a 40 cm, 50 [mu]m id fused silica capillary. Constant potential amperometry and pulsed amperometric detection were applied at the ITIES in which the organic phase was gelled. A miniaturized ITIES within a pipette tip was investigated, which resulted in improved separation e... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2761240 Tue, 01 Sep 2009 23:00:00 +0100 2761240 http://www.medworm.com/index.php?rid=2751113&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900124 The binding of olfactory receptors with odorant molecules initiates olfactory signal transduction, which leads to a cationic influx. In the present study, human embryonic kidney-293 cells were recombinantly engineered to co-express olfactory receptors I7 and gustatory cyclic nucleotide gated channels, which increased the cationic influx. The odorant-induced change in the membrane potential was measured in the extracellular region using microelectrode arrays. A biphasic electrical current stimulation was applied to the cells in order to increase the intrinsic cellular activity. Upon odorants recognition, the electrical cellular activity was enhanced following each electrical stimulation pulse. Compared with odorant-only stimulation, the electrical stimulation induced up to a fivefold increa... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2751113 Mon, 31 Aug 2009 23:00:00 +0100 2751113 http://www.medworm.com/index.php?rid=2751130&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900027 We have developed a new method for analyte preconcentration on a microfluidic device using a porous membrane fabricated via sol-gel chemistry. These porous membranes were fabricated within the channels of glass microfluidic devices exploiting laminar flow to bring an alcoholic sol-gel precursor (titanium isopropoxide in 2-propanol) into contact with an alcohol-water solution at a channel cross intersection. These two streams reacted at the fluidic interface to form a porous titania membrane. The thickness of the membrane could be altered by changing the [H2O]. Analyte concentration was accomplished by applying a voltage across the titania membrane. The level of analyte enrichment was monitored, and enrichment factors of above 4000 in 400 s were obtained for 2,7-dichlorofluorescein. (Source... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2751130 Sun, 30 Aug 2009 23:00:00 +0100 2751130 http://www.medworm.com/index.php?rid=2751129&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900068 Since most clinical assays are performed on cell-free serum or plasma, micro-analytical systems for blood tests require integrated on-chip microfluidics for the isolation of plasma or serum from crude blood samples. In this paper, we present a crossflow filtration method using novel silicon nano-filters for plasma separation. The microfluidic chip is made of a silicon substrate containing micropillar arrays, feed channels, side channels and nano-gap structures, sealed with a PDMS-glass compound cover. The design of the silicon filtration structures were optimized using numerical analysis and the optimal MEMS fabrication procedures were obtained. The filtration structures including nano-filters were characterized using SEM and subsequently used to isolate plasma from whole blood in a contin... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2751129 Sun, 30 Aug 2009 23:00:00 +0100 2751129 http://www.medworm.com/index.php?rid=2751128&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900111 In this research, a simple on-line microchip gel electrophoresis with ITP was applied for the concentration and separation of BSA and its immunoassay complex with mAb in a single cross form PMMA microchip. We investigated the ITP concentration effect in PMMA MCE using combination of leading electrolytes, terminating electrolytes and other factors. We realized an ITP-based concentration and separation of BSA and its immunoassay complexes in standard cross-channel microchip gel electrophoresis, which exceeded 2000-fold concentration of BSA immunocomplex using Tris-H3PO4 as a leading electrolyte and Tris-[gamma]-amino butyric acid as a terminating electrolyte. In addition, we also realized concentration of BSA sample in water, which was more than 20 000-fold and was the result of the concentr... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2751128 Sun, 30 Aug 2009 23:00:00 +0100 2751128 http://www.medworm.com/index.php?rid=2751127&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900112 A simple, sequential DNA pre-concentration and separation method by using a micro-CE chip integrated with a normally closed valve, which is activated by pneumatic suction, has been developed. The CE chip is fabricated using PDMS. A surface treatment technique for coating a polymer bilayer with an anionic charge is applied to modify the surface of the microchannel. A normally closed valve with anionic surface charges forms a nanoscale channel that only allows the passage of electric current but traps the DNA samples so that they are pre-concentrated. After the pre-concentration step, a pneumatic suction force is applied to the normally closed valve. This presses down the valve membrane, which reconnects the channels. The DNA samples are then moved into a separation channel for further separ... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2751127 Sun, 30 Aug 2009 23:00:00 +0100 2751127 http://www.medworm.com/index.php?rid=2751126&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900117 The preconcentration, separation, and electrochemical detection of a series of tetracycline (TC) antibiotics in a microfluidic channel were preformed. The electrophoretic experimental parameters to analyze TC, oxytetracycline, chlortetracycline, and doxycycline antibiotics were investigated with a cellulose-dsDNA-modified carbon paste electrode. Modification of the electrode improved detection performance by enhancing the signal-to-noise characteristics without surface fouling of the electrode. Field-amplified sample stacking and field-amplified sample injection techniques were employed for on-chip preconcentration of the TC series. The sensitivity of the method was improved 10 900-fold when compared with conventional MEKC-electrochemical detection analysis. The overall recoveries for TC, ... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2751126 Sun, 30 Aug 2009 23:00:00 +0100 2751126 http://www.medworm.com/index.php?rid=2751125&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900119 Microfluidics, especially droplet microfluidics, attracts more and more researchers from diverse fields, because it requires fewer materials and less time, produces less waste and has the potential of highly integrated and computer-controlled reaction processes for chemistry and biology. Electrorheological fluid, especially giant electrorheological fluid (GERF), which is considered as a kind of smart material, has been applied to the microfluidic systems to achieve active and precise control of fluid by electrical signal. In this review article, we will introduce recent results of microfluidic droplet manipulation, GERF and some pertinent achievements by introducing GERF into microfluidic system: digital generation, manipulation of "smart droplets" and droplet manipulation by GERF. Once it... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2751125 Sun, 30 Aug 2009 23:00:00 +0100 2751125 http://www.medworm.com/index.php?rid=2751124&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900120 A miniaturized metal semiconductor metal photodetector was developed as the core detector for chemiluminescence biosensor. The biosensor utilized the semiconductor manufacturing to fabricate the 83 interdigitated patterns of 250-nm metal line and 278-nm space in 100 [mu]m×100 [mu]m active region. The established real-time detector was operated at 0.4 V to ensure the maximal signal to background ratio of 3600 under illumination intensity of 1.46 mW/cm2. A chemiluminescence in the miniaturized chamber was successfully proposed to determine the model protein concentration in real-time analysis. Before the emission of light from the catalytic reaction of substrate, the model protein of streptavidin bound to horseradish peroxidase was successfully immobilized onto the sensor surface through th... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2751124 Sun, 30 Aug 2009 23:00:00 +0100 2751124 http://www.medworm.com/index.php?rid=2751123&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900126 This paper presents the development of a chemical sensor employing electronic-grade carbon nanotubes (EG-CNTs) as the active sensing element for sodium hypochlorite detection. The sensor, integrated in a PDMS-glass microfluidic chamber, was fabricated by bulk aligning of EG-CNTs between gold microelectrode pairs using dielectrophoretic technique. Upon exposure to sodium hypochlorite solution, the characteristics of the carbon nanotube chemical sensor were investigated at room temperature under constant current mode. The sensor exhibited responsivity, which fits a linear logarithmic dependence on concentration in the range of 1/32 to 8 ppm, a detection limit lower than 5 ppb, while saturating at 16 ppm. The typical response time of the sensor at room temperature is on the order of minutes a... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2751123 Sun, 30 Aug 2009 23:00:00 +0100 2751123 http://www.medworm.com/index.php?rid=2751122&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900127 A study of the influences of embedding artificial structures in a microfluidic device for CE with a free buffer solution is presented. Compared with conventional slab-gel electrophoresis, three major additional effects on the overall system performance are identified when sub-micron pillar arrays are integrated into a standard CE microsystem. Since DNA molecules have to migrate in-between and interact with the pillars, pillar geometry is first demonstrated to have a direct impact on the DNA motion pattern. Electric field re-distribution is another inevitable outcome when features of sub-micron dimensions are placed inside a microchannel. This effect is verified by a numerical simulation tool. Furthermore, the integration of the closely packed sub-micron structures dramatically increases th... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2751122 Sun, 30 Aug 2009 23:00:00 +0100 2751122 http://www.medworm.com/index.php?rid=2751121&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900128 This paper demonstrates a microfluidic chip for multiple immunoassays on electrospun (ES) nanofibrous membranes made of PVDF. This microchip enables the detection of multiple pairs of protein-protein interactions in one experiment by crossing parallel arrays of microchannels. This chip uses ESPVDF membrane with high specific surface area as the substrate to adsorb protein for immobilized immunoassays so that increased levels of protein adsorption may lower the LOD in immunoassays. We employ a simple and effective method for chip assembly by scotch tape to incorporate the ESPVDF membrane into the microchip. We believe that the present work will facilitate the development of methods for the on-site diagnosis of diseases whose detection is based on antigen-antibody recognition, and improve th... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2751121 Sun, 30 Aug 2009 23:00:00 +0100 2751121 http://www.medworm.com/index.php?rid=2751120&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900132 A PEG-NH2-based environmentally friendly surface modification strategy was developed for PDMS microchips to prevent protein adsorption and to enhance separation performance. PEG-NH2 was synthesized using a modified synthesis procedure. A two-step grafting method was used for PDMS modification. FTIR absorption by attenuated total reflection and contact angle measurements verified the successful grafting of PEG-NH2 onto the PDMS surface. Subsequent EOF Measurements and protein adsorption studies of PEG-modified PDMS microchips revealed noticeable EOF suppression and resistance to nonspecific protein adsorption for more than 30 days. Separation of four FITC-labeled amino acids was further demonstrated with high repeatability and reproducibility. Comparison of electrophoresis of 3-(2-furoyl)qu... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2751120 Sun, 30 Aug 2009 23:00:00 +0100 2751120 http://www.medworm.com/index.php?rid=2751119&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900134 In this study, trypsin- or [alpha]-chymotrypsin-immobilized microreactors prepared by a microfluidics-based enzyme-immobilization technique were studied for rapid sample preparation in proteomic analysis. The kinetic studies for hydrolysis of substrate by microreactors revealed that immobilized proteases had higher hydrolytic efficiency than those performed by in-solution digestion. The performance of the microreactors was evaluated by digesting cytochrome c and BSA. Protein digestion was achieved within a short period of time ([sim]5 min) at 30°C without any complicated reduction and alkylation procedures. The efficiency of digestion by trypsin-immobilized reactor was evaluated by analyzing the sequence coverage, which was 47 and 12% for cytochrome c and BSA, respectively. These values w... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2751119 Sun, 30 Aug 2009 23:00:00 +0100 2751119 http://www.medworm.com/index.php?rid=2751118&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900136 We present real-time, rapid detection of Mycoplasma pneumonia in PBS inside a Y-channel PDMS microfluidic device via optical fiber monitoring of latex immunoagglutination. The latex immunoagglutination assay was performed with serially diluted M. pneumonia solutions using highly carboxylated polystyrene particles of 390 and 500 nm diameter conjugated with monoclonal anti-M. pneumonia. Proximity optical fibers were located around the viewing cell of the device, which were used to measure the increase in 45° forward light scattering of the aggregated particles. The detection limit are slightly less than 50 pg mL-1 both for 390 and 500 nm microspheres and the detection time do not exceed 90 s. (Source: Electrophoresis) Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2751118 Sun, 30 Aug 2009 23:00:00 +0100 2751118 http://www.medworm.com/index.php?rid=2751117&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900141 In this study, anti-PSMA aptamers were immobilized onto the surface of a capture bed poised within a PMMA, microchip, which was fabricated into a high-throughput micro-sampling unit (HTMSU) used for the selective isolation of rare circulating prostate tumor cells resident in a peripheral blood matrix. The HTMSU capture bed consisted of 51 ultra-high-aspect ratio parallel curvilinear channels with a width similar to the prostate cancer cell dimensions. The surface density of the PSMA-specific aptamers on an ultraviolet-modified PMMA microfluidic capture bed surface was determined to be 8.4×1012 molecules/cm2. Using a linear velocity for optimal cell capture in the aptamer-tethered HTMSU (2.5 mm/s), a recovery of 90% of LNCaP cells (prostate cancer cell line; used as a model in this example... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2751117 Sun, 30 Aug 2009 23:00:00 +0100 2751117 http://www.medworm.com/index.php?rid=2751116&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900155 We developed a novel nanofluidic chip equipped with mercury microelectrodes, which enables electrochemical measurements to be made in 10-100 nm scale spaces (called extended nanospaces), and evaluated the performances. The effects of both space sizes and concentrations on the conductance (G) values of KCl solutions in extended nanospaces (216-5000 nm) were examined using impedance spectrometry. We found that the experimental G values in the extended nanospaces decreased non-linearly with decreasing KCl concentrations in the range of 10-2 to 10-7 M and could be explained by theoretical model taking account of surface charge density of on a glass surface. This was found to result from enhancement of proton concentrations of the confined solution owing to fast proton exchange between SiOH gro... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2751116 Sun, 30 Aug 2009 23:00:00 +0100 2751116 http://www.medworm.com/index.php?rid=2751115&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900159 A rapid (minutes) electrospray bead-based DNA hybridization detection technique is developed by spraying a mixture of hybridized and unhybridized silica nanocolloids. With proper far-field control by external electrodes, the trajectory of the ejected nanobeads from the electrospray is governed by specific harmonics of the Laplace equation, which select discrete polar angles along well-separated field maxima near the conducting Taylor cone. Due to Rayleigh fission and evaporation, beads of different size acquire different total charge after ejection and suffer different normal electrophoretic displacement such that they are ejected along well-separated field maxima and are deposited in distinct rings on an intersecting plane. As the hybridized DNA is of the same dimension as that of the nan... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2751115 Sun, 30 Aug 2009 23:00:00 +0100 2751115 http://www.medworm.com/index.php?rid=2751114&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900179 We report an insulator-based (or, electrodeless) dielectrophoresis utilizing microfabricated plastic membranes. The membranes with honeycomb-type pores have been fabricated by patterning the SU-8 layer on a substrate which was pretreated with self-assembled monolayer of octadecyltrichlorosilane for the easy release. The fabricated membrane was positioned between two electrodes and alternating current field was applied for the particle trap experiments. The particle could be trapped due to the dielectrophoresis force generated by the non-uniformities of the electric fields applied through the membranes with pores. Simulations using CFD-ACE+(CFD Research, Huntsville, Alabama) suggested that the dielectrophoresis force is stronger in the edge of the pores where the field gradient is highest. ... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2751114 Sun, 30 Aug 2009 23:00:00 +0100 2751114 http://www.medworm.com/index.php?rid=2733542&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900094 In this report, a pair of platinum wire electrodes was inserted in the main channel of a simple-cross PMMA microchip to perform on-chip alternating current-assisted proteolysis. Both terminals of the injection channel in the microchip were sharpened with a file to form sharp inlet tips to suck protein and trypsin solutions into the electrode-containing channel with the aid of a suction cup via the detection reservoir at the end of the chip. A solution containing BSA, cytochrome c, myoglobin, or hemoglobin was digested in the presence of alternating electric field after it was mixed with trypsin solution in the channel. The obtained digests were identified by MS with sequences that were comparable to those obtained by using conventional in-solution tryptic digestion while the digestion time... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2733542 Sun, 23 Aug 2009 23:00:00 +0100 2733542 http://www.medworm.com/index.php?rid=2733541&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900157 This work demonstrates a novel microfluidic in vitro cultivation system for embryos that improves their development using a partially constricted channel that mimics peristaltic muscle contraction. Conventional photolithography and a PDMS replica molding process were used to make straight or constricted microchannels. To investigate the effects of constriction geometry on embryonic development, different constriction widths of the channel were designed. Bovine embryos were loaded and incubated by simply placing them on a tilting machine to provide embryo movement via gravity. The fertilized embryos were cultivated on the microfluidic in vitro cultivation system until the blastocyst, hatching, or hatched blastocyst stages. To confirm the quality of blastocysts in the microfluidic channel, d... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2733541 Sun, 23 Aug 2009 23:00:00 +0100 2733541 http://www.medworm.com/index.php?rid=2733540&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900331 This article presents a simple method for trapping arrays of droplets relying on the designed microstructures of the microfluidic device, and this has been successfully used for parallel gas-liquid chemical reaction. In this approach, the trapping structure is composed of main channel, lateral channel and trapping region. Under a negative pressure, array droplets can be generated and trapped in the microstructure simultaneously, without the use of surfactant and the precise control of the flow velocity. By using a multi-layer microdevice containing the microstructures, single (pH gradient) and multiple gas-liquid reactions (metal ion-NH3 complex reaction) can be performed in array droplets through the transmembrane diffusion of the gas. The droplets with quantitative concentration gradient... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2733540 Sun, 23 Aug 2009 23:00:00 +0100 2733540 http://www.medworm.com/index.php?rid=2701853&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900246 In this study, the recombinant green fluorescent protein (GFP) was purified from intact Escherichia coli cells using preparative PAGE. In this purification process, cells disruption step is not needed. The cellular content of E. coli was drifted out electrically from cells and the negatively charged GFP was further electroeluted from polyacrylamide gel column. SEM investigation of the electrophoresed cells revealed substantial structural damage at the cellular level. This integrated purification technique has successfully recovered the intracellular GFP with a yield of 82% and purity of 95%. (Source: Electrophoresis) Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2701853 Fri, 14 Aug 2009 23:00:00 +0100 2701853 http://www.medworm.com/index.php?rid=2701855&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900228 Cultures of Oenococcus oeni, the most important malolactic bacterium, are used to induce malolactic fermentation in wine. Survival assays in two different wines confirmed that cells acclimated for 24 h in half-strength wine-like medium (acclimation medium) enhanced the malolactic performances. To investigate the effect of the pre-incubation phase on cell physiology, a proteomic study was carried out. Total protein extracts of acclimated and non-acclimated cell cultures (control) were analyzed by 2-D-PAGE. A total of 20 out of approximately 400 spots varied significantly. All the spots were identified by MS analysis and most of them were proteins involved in metabolism, transcription/translation processes and stress response. The results revealed the different physiological status between n... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2701855 Thu, 13 Aug 2009 23:00:00 +0100 2701855 http://www.medworm.com/index.php?rid=2701854&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900176 In this paper, we aimed to introduce a newly established red blood cells (RBCs) electrophoresis method hemoglobin release test (HRT) and tried to determine its significance. Human blood samples from [beta]-thalassemia patients and healthy controls were analyzed with HRT, which was carried out on starch-agarose mixed gel. First, the whole blood samples were electrophoresed for 2 h, then paused for 15 min and ran for 15 min by turns. This "pause-run-pause" experiment was performed for several turns and the total electrophoresis time lasted for about 6 h. The results showed that some other hemoglobin (Hb) components were released from the origin of each sample during the HRT, and the samples from [beta]-thalassemia patients released more Hb than the healthy controls. This finding demonstrates... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2701854 Thu, 13 Aug 2009 23:00:00 +0100 2701854 http://www.medworm.com/index.php?rid=2698912&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900177 A micropump-actuated negative pressure pinched injection method is developed for parallel electrophoresis on a multi-channel LIF detection system. The system has a home-made device that could individually control 16-port solenoid valves and a high-voltage power supply. The laser beam is excitated and distributes to the array separation channels for detection. The hybrid Glass-PDMS microfluidic chip comprises two common reservoirs, four separation channels coupled to their respective pneumatic micropumps and two reference channels. Due to use of pressure as a driving force, the proposed method has no sample bias effect for separation. There is only one high-voltage supply needed for separation without relying on the number of channels, which is significant for high-throughput analysis, and ... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2698912 Wed, 12 Aug 2009 23:00:00 +0100 2698912 http://www.medworm.com/index.php?rid=2698911&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200800798 Most CE methods for the analysis of phenols from olive oil use an aqueous electrolyte separation medium, although the importance of NACE is obvious, as this kind of CE seems to be more compatible with the hydrophobic olive oil matrix and could facilitate its direct injection. In the current work we develop a method involving SPE and NACE coupled to ESI-TOF MS. All the CE and ESI-TOF MS parameters were optimized in order to maximize the number of phenolic compounds detected and the sensitivity in their determination. Electrophoretic separation was carried out using a CE buffer system consisting of 25 mM NH4OAc/AcH in methanol/ACN (1/1 v/v) at an apparent pH value of 5.0. We studied in depth the effect of the nature and concentration of different electrolytes dissolved in different organic s... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2698911 Wed, 12 Aug 2009 23:00:00 +0100 2698911 http://www.medworm.com/index.php?rid=2698910&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900097 For the first time the versatility of CE is demonstrated for the separation of different types of anticancer drugs - anthracyclines and taxanes simultaneously. The use of these drugs in combination therapy for cancer has sparked interest in the development of methods for potential application. The simultaneous analysis of anthracyclines and taxanes can significantly increase a sample throughput of a clinical laboratory. The study shows the potential of CE for such a challenge: anthracyclines and taxanes were separated by CZE, MEKC and MEEKC. The MEEKC method was successfully applied to these compounds for the first time and was characterised by very short separation time, high efficiencies of peaks and was proven to be generic for the separation of different combinations of anthracyclines ... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2698910 Wed, 12 Aug 2009 23:00:00 +0100 2698910 http://www.medworm.com/index.php?rid=2698909&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900110 CE reactor (CER), which was developed as a tool for direct measurement of the dissociation kinetics of metal complexes, was successfully applied to the complexes of Escherichia coli ssDNA-binding protein (SSB) with ssDNA. The basic concept of CER is the application of CE separation process as a dissociation kinetic reactor for the complex, and the observation of the on-capillary dissociation reaction profile of the complex as the decrease of the peak height of the complex with increase of the migration time. The peak height of [SSB-ssDNA] decreases as the migration time increases since the degree of the decrease of [SSB-ssDNA] through the on-capillary dissociation reaction is proportional to the degree of the decrease of the peak height of [SSB-ssDNA]. The dissociation degree-time profiles... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2698909 Wed, 12 Aug 2009 23:00:00 +0100 2698909 http://www.medworm.com/index.php?rid=2698908&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900160 The enantiomerization of thioridazine (THD) using sulfated [beta]-CDs (S-[beta]-CDs) as chiral selectors in a citrate buffer at pH 3.0 was investigated by dynamic CE. The enantiomers of THD were well separated with dual CD systems consisting of S-[beta]-CD and a neutral CD. The electropherograms featuring a plateau formation, which indicated the occurrence of the enantiomerization of THD were obtained. The unified equation implemented in the software program DCXplorer was employed to evaluate elution profiles and to determine rate constants of the enantiomerization of THD. Activation parameters were evaluated from temperature-dependent measurements between 15 and 25°C with an increment of 2°C. The enantiomerization barriers of THD in two different electrophoretic systems were determined.... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2698908 Wed, 12 Aug 2009 23:00:00 +0100 2698908 http://www.medworm.com/index.php?rid=2694590&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900204 DNA methylation as an epigenetic modification of the human genome is under emphatic investigation. Several studies have demonstrated a role of DNA methylation in oncogenesis. In conjunction with histone modifications, DNA methylation may cause the formation of heterochromatin and thus mediate the inactivation of gene transcription. It is important to develop methods that allow for an accurate quantification of the amount of DNA methylation in particular DNA regions, to gain information concerning the threshold of methylation levels necessary for gene inactivation. In this article, a CGE method with on-column LIF detection using SYBR Green is compared with a conventional slab-gel electrophoresis. We thus investigate the validity to analyze DNA methylation in the samples of a combined bisulf... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2694590 Wed, 12 Aug 2009 23:00:00 +0100 2694590 http://www.medworm.com/index.php?rid=2694598&cid=s_33767_60_f&fid=33767&url=http%3A%2F%2Fdx.doi.org%2F10.1002%252Felps.200900003 A dielectrophoretic (DEP) chip with an SU-8 microcavity array for trapping single particle/cell is designed, fabricated, and quantitatively examined by simulations and experiments. The particles can be easily trapped in or pulled out of the microcavity based on negative or positive DEP force, respectively. The nonuniform electric field is formed in relation to the configuration of the microcavity array, i.e. its diameter and spacing, as described in the simulation results. In order to investigate the effects of the microcavity, two maximal flow rates for trapping particles in the microcavity and washing them away from the microcavity under different DEP voltages are determined by experiments. As the experimental results show, the extrastationary effects, provided as a particle is trapped i... Electrophoresis journals http://www.medworm.com/rss/comments.php?id=2694598 Tue, 11 Aug 2009 23:00:00 +0100 2694598