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572 records returned

Insoluble and Flexible Silk Films Containing Glycerol.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We directly prepared insoluble silk films by blending with glycerol and avoiding the use of organic solvents. The ability to blend a plasticizer like glycerol with a hydrophobic protein like silk and achieve stable material systems above a critical threshold of glycerol is an important new finding with importance for green chemistry approaches to new and more flexible silk-based biomaterials. The aqueous solubility, biocompatibility, and well-documented use of glycerol as a plasticizer with other biopolymers prompted its inclusion in silk fibroin solutions to assess impact on silk film behavior. Processing was performe...
Source: Biomacromolecules - November 18, 2009 Category: Biochemistry Authors: Lu S, Wang X, Lu Q, Zhang X, Kluge JA, Uppal N, Omenetto F, Kaplan DL Tags: Biomacromolecules Source Type: journals

Injectable, Highly Flexible, and Thermosensitive Hydrogels Capable of Delivering Superoxide Dismutase.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Injectable hydrogels are attractive for cell and drug delivery. In this work, we synthesized a family of injectable, biodegradable, fast gelling and thermosensitive hydrogels based on N-isopropylacrylamide (NIPAAm), acrylic acid (AAc), dimethyl-gamma-butyrolactone acrylate (DBA), and 2-hydroxyethyl methacrylate-poly(trimethylene carbontate) (HEMAPTMC) macromer. Type I collagen was composited with the hydrogels to improve their biocompatibility. The hydrogel copolymer solutions were readily injectable at 4 degrees C. The solutions exhibited thermal transition temperatures ranging from 23.6 to 24.5 degrees C and were cap...
Source: Biomacromolecules - November 17, 2009 Category: Biochemistry Authors: Li Z, Wang F, Roy S, Sen CK, Guan J Tags: Biomacromolecules Source Type: journals

Enzyme-Catalyzed Polycondensation of Polyester Macrodiols with Divinyl Adipate: A Green Method for the Preparation of Thermoplastic Block Copolyesters.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Enzyme-catalyzed polycondensation for the synthesis of block copolymers was reported for the first time. Thermoplastic block copolyesters containing poly[(R)-3-hydroxybutyrate] (PHB) and poly[(R)-3-hydroxyoctanoate] (PHO) blocks were enzymatically prepared by one- or two-step lipase-catalyzed polycondensation. Novozym 435-catalyzed reaction of PHB-diol (M(n) of 3100 g/mol, GPC), PHO-diol (M(n) of 3200 g/mol, GPC), and divinyl adipate gave block poly(HB-co-HO) (M(n) of 9800 g/mol, GPC) with randomly arranged blocks in 55% yield. In two-step polycondensations, Novozym 435-catalyzed reaction of PHB-diol and divinyl adipat...
Source: Biomacromolecules - November 17, 2009 Category: Biochemistry Authors: Dai S, Xue L, Zinn M, Li Z Tags: Biomacromolecules Source Type: journals

Preparation of Thermoresponsive Anionic Copolymer Brush Surfaces for Separating Basic Biomolecules.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Poly(N-isopropylacrylamide-co-acrylic acid-co-N-tert-butylacrylamide) (poly(IPAAm-co-AAc-co-tBAAm) brush grafted silica beads were prepared through a surface-initiated atom transfer radical polymerization (ATRP) with CuCl/CuCl(2)/Me(6)TREN catalytic system in 2-propanol at 25 degrees C for 4 h. The prepared beads were characterized by chromatographic analysis. Basic analytes, catecholamine derivatives, and angiotensin peptides could be separated by a short column length containing the beads because of its high densely grafted copolymer structure. Chromatograms for catecholamine derivatives were obtained with high resol...
Source: Biomacromolecules - November 17, 2009 Category: Biochemistry Authors: Nagase K, Kobayashi J, Kikuchi A, Akiyama Y, Kanazawa H, Annaka M, Okano T Tags: Biomacromolecules Source Type: journals

DNA Condensation by Chiral alpha-Methylated Polyamine Analogues and Protection of Cellular DNA from Oxidative Damage.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Polyamines are essential molecules supporting the structure, conformation, and function of nucleic acids and proteins. We studied stereoisomers of alpha,alpha'-dimethylated spermine [(R,R)-Me(2)Spm, (S,S)-Me(2)Spm, (R,S)-Me(2)Spm] for their ability to provoke DNA condensation and protect DNA from damage. (R,R)- and (R,S)-Me(2)Spm displayed more efficient condensing ability than spermine, with significantly lower EC(50) (concentration for 50% compaction) values (p </= 0.01). However, spermine exerted slightly more duplex stabilization than Me(2)Spm. Condensation resulted in nanoparticles with hydrodynamic radii betwe...
Source: Biomacromolecules - November 17, 2009 Category: Biochemistry Authors: Nayvelt I, Hyvönen MT, Alhonen L, Pandya I, Thomas T, Khomutov AR, Vepsäläinen J, Patel R, Keinänen TA, Thomas TJ Tags: Biomacromolecules Source Type: journals

Physical Hydrogels Photo-Cross-Linked from Self-Assembled Macromers for Potential Use in Tissue Engineering.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
To engineer artificial extracellular matrices (ECMs) enabling degradation-independent cell migration that mimicked nonproteolytic cell migration through physically stabilized ECMs in biological systems, polymers having a hydrophilic chain flanked by a terminal self-assembling leucine zipper domain and a terminal photoreactive acrylate group were molecularly engineered to form photo-cross-linkable physical hydrogels. Physical association of the leucine zippers resulted in multifunctional macromers, which were photo-cross-linkable into hydrogels. Gel formation was confirmed by rheological measurements. The physical natur...
Source: Biomacromolecules - November 17, 2009 Category: Biochemistry Authors: Liu B, Lewis AK, Shen W Tags: Biomacromolecules Source Type: journals

Tricarbonyl-Rhenium Complexes of a Thiol-Functionalized Amphoteric Poly(amidoamine).Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
An amphoteric thiol-functionalized poly(amidoamine) nicknamed ISA23SH(10%) was synthesized. Rhenium complexes 1 and 2, containing 0.5 and 0.8 equiv of rhenium, respectively, were easily obtained by reacting ISA23SH(10%) with [Re(CO)(3)(H(2)O)(3)](CF(3)SO(3)) in aqueous solution at pH 5.5. Both ISA23SH(10%), and its rhenium complexes were soluble in water under physiological conditions. The resultant solutions were stable, even in the presence of cysteine. Rhenium chelation occurred through the S and N atoms of the cysteamine moiety, as demonstrated by (1)H, (13)C, and (15)N NMR spectroscopy. The diffusion coefficients ...
Source: Biomacromolecules - November 16, 2009 Category: Biochemistry Authors: Donghi D, Maggioni D, D'Alfonso G, Amigoni F, Ranucci E, Ferruti P, Manfredi A, Fenili F, Bisazza A, Cavalli R Tags: Biomacromolecules Source Type: journals

Comparison of the Mechanical Properties of Cellulose and Starch Films.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Some effects of water at levels up to 25% (dry solids basis db) on regenerated cellulose films with a thickness of 100 mum were investigated by dynamic vapor sorption (DVS), X-ray diffraction, tensile testing, and proton-nuclear magnetic resonance (NMR). The sorption isotherm fitted by the D'Arcy and Watt model and the increase in NMR T(2) with water content suggest that a mobile water fraction appears at water contents above 10%db. Water absorption increased the crystallinity of cellulose films from 31% (dry) to 38% (25%db) and altered the dimensions of crystallites. Mechanical measurements on planar and notched sampl...
Source: Biomacromolecules - November 12, 2009 Category: Biochemistry Authors: Sun S, Mitchell JR, Macnaughtan W, Foster TJ, Harabagiu V, Song Y, Zheng Q Tags: Biomacromolecules Source Type: journals

Controlled Release and Entrapment of Enantiomers in Self-Assembling Scaffolds Composed of beta-Sheet Peptides.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
As a first step toward utilizing self-assembling peptide scaffolds to create tunable matrices for drug delivery, peptide RADAFI and RADAFII, containing the same amino acid composition but different positions of one phenylalanine residue, scaffolds were prepared for controlled release of chiral enantiomers. The release behaviors depended on the network nanostructures and the guest chirality and were well tailored via loading different amounts of guests. This contribution addressed the relationships among the peptide sequence, the network nanoarchitecture, and the controlled release. RADAFII systems provided a means of c...
Source: Biomacromolecules - November 11, 2009 Category: Biochemistry Authors: Zhao Y, Tanaka M, Kinoshita T, Higuchi M, Tan T Tags: Biomacromolecules Source Type: journals

Evidence of Mineralization Activity and Supramolecular Assembly by the N-Terminal Sequence of ACCBP, a Biomineralization Protein That Is Homologous to the Acetylcholine Binding Protein Family.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Several biomineralization proteins that exhibit intrinsic disorder also possess sequence regions that are homologous to nonmineral associated folded proteins. One such protein is the amorphous calcium carbonate binding protein (ACCBP), one of several proteins that regulate the formation of the oyster shell and exhibit 30% conserved sequence identity to the acetylcholine binding protein sequences. To gain a better understanding of the ACCBP protein, we utilized bioinformatic approaches to identify the location of disordered and folded regions within this protein. In addition, we synthesized a 50 AA polypeptide, ACCN, re...
Source: Biomacromolecules - November 11, 2009 Category: Biochemistry Authors: Amos FF, Ndao M, Evans JS Tags: Biomacromolecules Source Type: journals

Binding of beta-Lactolobulin to Pectins Varying in their Overall and Local Charge Density.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The formation of complexes between proteins and polysaccharides is of great importance for many food systems like foams, emulsions, acidified milk drinks, and so on. The complex formation between beta-lactoglobulin (beta-lg) and pectins with a well-defined physicochemical fine structure has been studied to elucidate the influence of overall charge and local charge density of pectin on the complex formation. Binding isotherms of beta-lg to pectin are constructed using fluorescence anisotropy, which is shown to be an excellent technique for this purpose, as it is fast and requires low sample volumes. From the binding iso...
Source: Biomacromolecules - November 11, 2009 Category: Biochemistry Authors: Sperber BL, Cohen Stuart MA, Schols HA, Voragen AG, Norde W Tags: Biomacromolecules Source Type: journals

Synthesis and Evaluation of Phenylalanine-Modified Hyperbranched Poly(amido amine)s as Promising Gene Carriers.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, the HPAMAM was further modified on the terminal amino groups with phenylalanine to various degrees (HPAMAM-PHE30, PHE45, PHE60). We showed that HPAMAM and HPAMAM-PHEs were all able to form complexes with plasmid DNA (pDNA) at various mass ratios. The cytotoxicity and transfection efficiencies of these polymers were evaluated in SMMC-7721 and COS-7 cell lines. The PHE modifications affected the cell transfection efficiency significantly. The HPAMAM-PHE60 was the most efficient, with transfection activities consistently higher than the commercial transfection reagent PEI. Our study demonstrated that HPAMAM-PHE...
Source: Biomacromolecules - November 11, 2009 Category: Biochemistry Authors: Wang X, He Y, Wu J, Gao C, Xu Y Tags: Biomacromolecules Source Type: journals

Site-Selective Binding of Human Serum Albumin by Palmatine: Spectroscopic Approach.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, fluorescence spectroscopy in combination with UV-vis absorption spectroscopy and circular dichroism (CD) spectroscopy was employed to investigate the high affinity binding of palmatine to human serum albumin (HSA) under the physiological conditions. In the mechanism discussion it was proved that the fluorescence quenching of HSA by palmatine is a result of the formation of palmatine/HSA complex. Binding parameters calculating from Stern-Volmer method and Scatchard method showed that palmatine bind to HSA with the binding affinities of the order 10(4) L.mol(-1). The thermodynamic parameters studies revealed t...
Source: Biomacromolecules - November 9, 2009 Category: Biochemistry Authors: Hu YJ, Ou-Yang Y, Dai CM, Liu Y, Xiao XH Tags: Biomacromolecules Source Type: journals

Kinetics of nanoparticle targeting by dissipative particle dynamics simulations.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Dissipative particle dynamics simulations are applied to study nanoparticle targeting to a cell surface containing a high concentration of receptors. We found that the normalized number of bound ligands follows an exponential growth function 1 - exp(-t/tau), with the lifetime tau increasing as a function of the binding strength. With increasing binding energy, the shape of the adsorbed nanoparticle becomes ellipsoidal due to a large number of stably bound ligands, most of which are positioned on the nanoparticle periphery. For a low degree of functionalization of homogeneously distributed ligands, the kinetics of nanop...
Source: Biomacromolecules - November 9, 2009 Category: Biochemistry Authors: Djohari H, Dormidontova EE Tags: Biomacromolecules Source Type: journals

Relation between chemical structure and supramolecular organization of synthetic lignin-pectin particles.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
PMID: 19894766 [PubMed - in process] (Source: Biomacromolecules)
Source: Biomacromolecules - November 9, 2009 Category: Biochemistry Authors: Habrant A, Gaillard C, Ralet MC, Lairez D, Cathala B Tags: Biomacromolecules Source Type: journals

Structure and Dynamics of Aromatic Residues in Spider Silk: 2D Carbon Correlation NMR of Dragline Fibers.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The structure of aromatic residues in spider silk has remained relatively uncharacterized. This is primarily due to the relatively low abundance of aromatic residues in dragline spider silk. NMR characterization has been further hindered by the inability to (13)C-isotopically enrich these amino acids in the silk effectively. In the present contribution, it is shown that feeding spiders an aqueous solution of [U-(13)C/(15)N]-l-phenylalanine (13)C-enriches Tyr to a level of 20-30% in dragline spider silk. This enables the collection of 2D through-bond (13)C double quantum/single quantum (DQ/SQ) correlation spectra with t...
Source: Biomacromolecules - November 6, 2009 Category: Biochemistry Authors: Izdebski T, Akhenblit P, Jenkins JE, Yarger JL, Holland GP Tags: Biomacromolecules Source Type: journals

Modifications of Hyaluronan Influence the Interaction with Human Bone Morphogenetic Protein-4 (hBMP-4).Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, we have demonstrated that the modification of hyaluronan (hyaluronic acid; Hya) with sulfate groups led to different binding affinities for recombinant human bone morphogenetic protein-4 (rhBMP-4). The high-sulfated sHya2.8 (average degree of sulfation (D.S.) 2.8) exhibited the tightest interaction with rhBMP-4, followed by the low-sulfated sHya1.0, as determined with surface plasmon resonance (SPR), ELISA, and competition ELISA. Unmodified Hya, chondroitin-sulfate (CS), and heparan sulfate (HS) showed significantly less binding affinity. SPR data could be fitted to an A + B = AB Langmuir model and binding c...
Source: Biomacromolecules - November 6, 2009 Category: Biochemistry Authors: Hintze V, Moeller S, Schnabelrauch M, Bierbaum S, Viola M, Worch H, Scharnweber D Tags: Biomacromolecules Source Type: journals

Comment on "J- and H-Aggregates of 5,10,15,20-Tetrakis-(4-sulfonatophenyl)-porphyrin and Interconversion in PEG-b-P4VP Micelles"Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
PMID: 19891495 [PubMed - as supplied by publisher] (Source: Biomacromolecules)
Source: Biomacromolecules - November 6, 2009 Category: Biochemistry Authors: Moreno-Villoslada I, Murakami T, Nishide H Tags: Biomacromolecules Source Type: journals

Reply to Comment on "J- and H-Aggregates of 5,10,15,20-Tetrakis-(4-sulfonatophenyl)-porphyrin and Interconversion in PEG-b-P4VP Micelles"Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
PMID: 19891497 [PubMed - as supplied by publisher] (Source: Biomacromolecules)
Source: Biomacromolecules - November 6, 2009 Category: Biochemistry Authors: Zhao L, Ma R, Li J, Li Y, An Y, Shi L Tags: Biomacromolecules Source Type: journals

Gas-in-Liquid Foam Templating as a Method for the Production of Highly Porous Scaffolds.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In the present work, a novel synthetic methodology for the preparation of scaffold of biopolymeric nature is described. In particular, a porous gelatin scaffold was prepared by foam templating. The gas phase, nitrogen, was generated by means of the reaction between sulfamic acid and sodium nitrite in situ a concentrated solution of gelatin and in the presence of a suitable polymeric surfactant in association with sodium dodecyl sulfate. The foam was prepared at a temperature of 45 degrees C and then let gel at 5 degrees C. After purification, the physical gel was auto-cross-linked with EDC and freeze-dried. The scaffol...
Source: Biomacromolecules - November 6, 2009 Category: Biochemistry Authors: Barbetta A, Gumiero A, Pecci R, Bedini R, Dentini M Tags: Biomacromolecules Source Type: journals

Direct Chemical Cross-Linking of Platelet-Derived Growth Factor-BB to the Demineralized Bone Matrix Improves Cellularization and Vascularization.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In previous studies, we have described the use of demineralized bone matrix (DBM) as a carrier for the localized delivery system of growth factors in vitro and in vivo. The aim of the present work was to develop a direct chemical approach to immobilize the platelet-derived growth factor-BB (PDGF-BB) on DBM with cross-linking reagents. The amount of PDGF-BB covalently immobilized on DBM was significantly increased. The increased proliferation of fibroblasts demonstrated that the biological activity of PDGF-BB was not significantly reduced by cross-linking. Compared with control groups, there was a statistically signific...
Source: Biomacromolecules - November 5, 2009 Category: Biochemistry Authors: Chen L, He Z, Chen B, Zhao Y, Sun W, Xiao Z, Zhang J, Yang M, Gao Z, Dai J Tags: Biomacromolecules Source Type: journals

Inducing Demixing of Semidilute and Highly Compatible Biopolymer Mixtures in the Presence of a Strong Polyelectrolyte.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The weak intermacromolecular interactions caused by the presence of a complexing agent in a two-phase biopolymer mixture can affect its phase equilibrium and morphology. In this communication, the attempt was made to induce demixing in semidilute and highly compatible sodium caseinate/sodium alginate system (SC-SA) mixtures in the presence of a sodium salt of dextran sulfate (DSS) at pH 7.0 (above the isoelectrical point of caseins), and to characterize phase equilibrium, intermacromolecular interactions, and structure of such systems by rheo-small angle light scattering (SALS), optical microscopy (OM), phase analysis,...
Source: Biomacromolecules - November 2, 2009 Category: Biochemistry Authors: Antonov YA, Moldenaers P Tags: Biomacromolecules Source Type: journals

Macromolecular Cobalt Carbonyl Complexes Encapsulated in a Click-Cross-Linked Micelle Structure as a Nanoparticle To Deliver Cobalt Pharmaceuticals.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Block copolymers poly(trimethylsilyl propargyl methacrylate)-block-poly(poly(ethylene glycol) methyl ether methacrylate) (P(TMS-PAMA)-b-P(PEGMA)) were synthesized using reversible addition-fragmentation chain transfer (RAFT) polymerization. Subsequent removal of the trimethylsilyl protective groups on the P(TMS-PAMA)(24)-b-P(PEGMA)(40) polymer with tetra-n-butylammonium fluoride hydrate lead to the polymer P(PAMA)(24)-b-P(PEGMA)(40) with pendant alkyne groups, which self-assembled in aqueous solution into micelles with hydrodynamic diameters of less than 20 nm. The alkyne groups in the core took on two functions, actin...
Source: Biomacromolecules - November 2, 2009 Category: Biochemistry Authors: Withey AB, Chen G, Nguyen TL, Stenzel MH Tags: Biomacromolecules Source Type: journals

pH-Triggered Disassembly in a Caged Protein Complex.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Self-assembling protein cage structures have many potential applications in nanotechnology, one of which is therapeutic delivery. For intracellular targeting, pH-controlled disassembly of virus-like particles and release of their molecular cargo is particularly strategic. We investigated the potential of using histidines for introducing pH-dependent disassembly in the E2 subunit of pyruvate dehydrogenase. Two subunit interfaces likely to disrupt stability, an intratrimer interface (the N-terminus) and an intertrimer interface (methionine-425), were redesigned. Our results show that changing the identity of the putative...
Source: Biomacromolecules - October 29, 2009 Category: Biochemistry Authors: Dalmau M, Lim S, Wang SW Tags: Biomacromolecules Source Type: journals

Wet-Spinning of Regenerated Silk Fiber from Aqueous Silk Fibroin Solution: Discussion of Spinning Parameters.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Discussion of Spinning Parameters. Biomacromolecules. 2009 Oct 27; Authors: Yan J, Zhou G, Knight DP, Shao Z, Chen X Regenerated silk fibroin (RSF) fibers were obtained by extruding a concentrated aqueous silk fibroin solution into an ammonium sulfate coagulation bath. A custom-made simplified industrial-type wet-spinning device with continuous mechanical postdraw was used. The effect of dope concentration, coagulation bath, extrusion rate, and postdraw treatment on the morphology of RSF fiber was examined. The results showed that although RSF fiber could be formed with dope concentration between 13 and 19% (w/...
Source: Biomacromolecules - October 27, 2009 Category: Biochemistry Authors: Yan J, Zhou G, Knight DP, Shao Z, Chen X Tags: Biomacromolecules Source Type: journals

Elastic Moduli of Cellulose Nanoparticle-Reinforced Composites: A Micromechanical Model.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A model for the elastic coefficients of fiber-reinforced materials is applied toward the analysis of the tensile and shear moduli of nanocomposites reinforced by rod-like cellulose nanoparticles. Our formalism integrates results from percolation theory with micromechanical and effective medium approaches. Polydispersity in the fiber length distribution and anisotropies in the stiffness coefficients of cellulose nanoparticles are taken into account explicitly. Results from calculations employing our model display reasonable agreement with experimental measurements of the moduli as functions of the filler volume fraction...
Source: Biomacromolecules - October 23, 2009 Category: Biochemistry Authors: Prokhorova DA, Chatterjee AP Tags: Biomacromolecules Source Type: journals

Chemoselective Cross-Linking and Functionalization of Alginate via Staudinger Ligation.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, we demonstrate the applicability of functionalized alginate to serve as a platform for the covalent cross-linking or immobilization of complementary phosphine functionalized groups via the chemoselective Staudinger ligation scheme. Azide groups were covalently linked to alginate through a heterobifunctional polyethylene glycol (PEG) linker and carbodiimide. Degree of azide functionalization was varied as a function of carbodiimide concentration and determined by proton nuclear magnetic resonance ((1)H NMR) and infrared spectroscopy. Spontaneous and covalently cross-linked alginate-PEG gels were generated via...
Source: Biomacromolecules - October 22, 2009 Category: Biochemistry Authors: Gattás-Asfura KM, Stabler CL Tags: Biomacromolecules Source Type: journals

Compact Polyelectrolyte Complexes: "Saloplastic" Candidates for Biomaterials.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Precipitates of polyelectrolyte complexes were transformed into rugged shapes suitable for bioimplants by ultracentrifugation in the presence of high salt concentration. Salt ions dope the complex, creating a softer material with viscous fluid-like properties. Complexes that were compacted under the centrifugal field (CoPECs) were made from poly(diallyldimethyl ammonium), PDADMA, as polycation, and poly(styrene sulfonate), PSS, or poly(methacrylic acid), PMAA, as polyanion. Dynamic mechanical testing revealed a rubbery plateau at lower frequencies for PSS/PDADMA with moduli that decreased with increasing salt concentra...
Source: Biomacromolecules - October 18, 2009 Category: Biochemistry Authors: Porcel CH, Schlenoff JB Tags: Biomacromolecules Source Type: journals

Controlled Integration of Polymers into Viral Capsids.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this paper, we describe the controlled incorporation of two synthetic polymers with different structures in the cowpea chlorotic mottle virus (CCMV) capsid. Poly(ethylene glycol) (PEG) chains have been attached to the amine groups of lysine residues on the outer surface of the viral capsid. The functionalization of CCMV with PEG chains provoked a slow but irreversible dissociation of the virus into PEG-coat protein (CP) subunits, likely due to steric interference between the protein-protein subunits as a result of the presence of the PEG chains. This thermodynamic instability, however, can be overcome if a second po...
Source: Biomacromolecules - October 18, 2009 Category: Biochemistry Authors: Comellas-Aragonès M, de la Escosura A, Dirks AT, van der Ham A, Fusté-Cuñé A, Cornelissen JJ, Nolte RJ Tags: Biomacromolecules Source Type: journals

Surface-Initiated ATRP Modification of Tissue Culture Substrates: Poly(glycerol monomethacrylate) as an Antifouling Surface.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Surface-initiated atom transfer radical polymerization (SI-ATRP) can be used to produce conformal coatings of controlled thickness on virtually any surface, providing to it specific physico-chemical and biological properties. Here we have tackled the problem of modulating cell adhesion on typical culture substrates; tissue culture polystyrene (TCPS) offers a number of favorable properties (optical transparency, chemical stability, sterilizability, availability in a wide variety of shapes) but somehow limited biological function. A fine tuning of cell adhesion can, on the contrary, allow better control cell phenotype du...
Source: Biomacromolecules - October 14, 2009 Category: Biochemistry Authors: Patrucco E, Ouasti S, Vo CD, De Leonardis P, Pollicino A, Armes SP, Scandola M, Tirelli N Tags: Biomacromolecules Source Type: journals

Chitosan-graft-6-mercaptonicotinic Acid: Synthesis, Characterization, and Biocompatibility.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Thiolated chitosans are relatively new thiolated biopolymers exhibiting mucoadhesive, enzyme inhibitory, and permeation enhancing properties. A drawback, however, is their pH dependent reactivity. The aim of this study was therefore to develop a novel thiolated chitosan showing a non pH dependent reactivity of its thiol groups. For this purpose, 6-mercaptonicotinic acid (6-MNA) was covalently attached to chitosan by a carbodiimide mediated reaction. The obtained conjugate was characterized in vitro by quantification of immobilized thiol groups, cytotoxicity, in situ gelling properties, and disulfide bond formation at d...
Source: Biomacromolecules - October 11, 2009 Category: Biochemistry Authors: Millotti G, Samberger C, Fröhlich E, Bernkop-Schnürch A Tags: Biomacromolecules Source Type: journals

Comparisons of Recombinant Resilin-like Proteins: Repetitive Domains Are Sufficient to Confer Resilin-like Properties.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Two novel recombinant proteins An16 and Dros16 have recently been generated. These recombinant proteins contain, respectively, sixteen copies of an 11 amino acid repetitive domain (AQTPSSQYGAP) observed in a resilin-like gene from Anopheles gambiae and sixteen copies of a 15 amino acid repetitive domain (GGRPSDSYGAPGGGN) observed in the first exon of the Drosophila melanogaster CG15920 gene. We compare structural characteristics of the proteins and material properties of resulting biopolymers relative to Rec1-resilin, a previously characterized resilin-like protein encoded by the first exon of the Drosophila melanogast...
Source: Biomacromolecules - October 11, 2009 Category: Biochemistry Authors: Lyons RE, Nairn KM, Huson MG, Kim M, Dumsday G, Elvin CM Tags: Biomacromolecules Source Type: journals

Enzyme-Mediated Redox Initiation for Hydrogel Generation and Cellular Encapsulation.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A rapid, water-soluble enzyme-mediated radical chain initiation system involving glucose oxidase and Fe(2+) generated hydrogels within minutes at 25 degrees C and in ambient oxygen. The initiation components were evaluated for their effect on polymerization rates of hydroxyethyl acrylate-poly(ethylene glycol)(575) diacrylate comonomer solutions using near-infrared spectroscopy. Increasing glucose concentration increased polymerization rates until reaching a rate plateau above 1 x 10(-3) M of glucose. A square root dependence of the initial polymerization rate on Fe(2+) concentration was observed between 1.0 x 10(-4) M ...
Source: Biomacromolecules - October 11, 2009 Category: Biochemistry Authors: Johnson LM, Fairbanks BD, Anseth KS, Bowman CN Tags: Biomacromolecules Source Type: journals

Encapsulation of Living Bifidobacteria in Ultrathin PVOH Electrospun Fibers.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study shows the application of the electrospinning technique as a viable method for the encapsulation and stabilization of bifidobacterial strains. Poly(vinyl alcohol) (PVOH) was used as the encapsulating material because it is generally recognized as safe (GRAS), has a high oxygen barrier when dry, and is water soluble, hence allowing easy recovery of the bacteria for viability testing. A coaxial setup was used for encapsulation, and the so-obtained electrospun fibers had a mean diameter of ca. 150 nm. Incorporation of B. animalis Bb12 led to a decrease in melting point and crystallinity of the PVOH fibers and to an ...
Source: Biomacromolecules - October 11, 2009 Category: Biochemistry Authors: López-Rubio A, Sanchez E, Sanz Y, Lagaron JM Tags: Biomacromolecules Source Type: journals

Synthesis, Degradation, and Cytotoxicity of Multiblock Poly(epsilon-caprolactone urethane)s Containing Gemini Quaternary Ammonium Cationic Groups.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Novel cationic biodegradable multiblock poly(epsilon-caprolactone urethane)s that contain gemini quaternary ammonium side groups on the hard segments were developed. To obtain these polyurethanes, a new l-lysine-derivatized diamine containing gemini quaternary ammonium side groups (GA8) was first synthesized and characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectra (NMR), mass spectrometry (MS), and high-resolution mass spectra (HRMS). Then a series of gemini poly(epsilon-caprolactone urethane)s were designed and prepared using l-lysine ethyl ester diisocyanate (LDI), poly(...
Source: Biomacromolecules - October 11, 2009 Category: Biochemistry Authors: Ding M, Li J, Fu X, Zhou J, Tan H, Gu Q, Fu Q Tags: Biomacromolecules Source Type: journals

Simple Agarose-Chitosan Gel Composite System for Enhanced Neuronal Growth in Three Dimensions.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A simplified approach to increase neuronal attachment on an agarose hydrogel was proposed by blending agarose with another biocompatible polysaccharide, chitosan. The stiffness of the agarose gel was maintained despite the inclusion of chitosan, as determined by rheological tests. The structure of the blended hydrogels was characterized using light microscopy and scanning electron microscopy. An in vitro cell study revealed that the blends promoted neuron adhesion. The concentration of chitosan in the hydrogel had great influence on the morphology of neurons. An optimum range of chitosan concentration in agarose gel, t...
Source: Biomacromolecules - October 11, 2009 Category: Biochemistry Authors: Cao Z, Gilbert RJ, He W Tags: Biomacromolecules Source Type: journals

Smooth Muscle Cell Phenotype Modulation and Contraction on Native and Cross-Linked Polyelectrolyte Multilayers.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Smooth muscle cells convert between a motile, proliferative "synthetic" phenotype and a sessile, "contractile" phenotype. The ability to manipulate the phenotype of aortic smooth muscle cells with thin biocompatible polyelectrolyte multilayers (PEMUs) with common surface chemical characteristics but varying stiffness was investigated. The stiffness of (PAH/PAA) PEMUs was varied by heating to form covalent amide bond cross-links between the layers. Atomic force microscopy (AFM) showed that cross-linked PEMUs were thinner than those that were not cross-linked. AFM nanoindentation demonstrated that the Young's modulus ran...
Source: Biomacromolecules - October 8, 2009 Category: Biochemistry Authors: Moussallem MD, Olenych SG, Scott SL, Keller TC, Schlenoff JB Tags: Biomacromolecules Source Type: journals

Associative Network Based on Cyclodextrin Polymer: A Model System for Drug Delivery.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Associative networks have been elaborated by mixing in aqueous media a cyclodextrin polymer to a dextran bearing adamantyl groups. The two polymers interact mainly via inclusion complexes between adamantyl groups and cyclodextrin cavities, as evidenced by the high complexation constants determined by isothermal titration microcalorimetry ( approximately 10(4) L mol(-1)). Additional interaction mechanisms participating in the strength of the network, mainly hydrogen bonding and electrostatic interactions, are sensitive to the pH and ionic strength of the medium, as shown by pH-dependent rheological properties. The loadi...
Source: Biomacromolecules - October 8, 2009 Category: Biochemistry Authors: Layre AM, Volet G, Wintgens V, Amiel C Tags: Biomacromolecules Source Type: journals

Cationic Fluorene-Based Conjugated Polyelectrolytes Induce Compaction and Bridging in DNA.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The cationic conjugated polymer (CCP), poly{9,9-bis[N,N-(trimethylammonium)hexyl]fluorene-co-1,4-phenylene} iodide (PFP-NR3) induces compaction in DNA in an acetonitrile/water mixture, as seen by fluorescence microscopy. At high concentrations of PFP-NR3, some chain structures still appear to exist. However, these are larger than normal DNA coils and have "beads" of enhanced fluorescence along the chain. These structures have also been imaged on freshly cleaved mica surfaces using atomic force microscopy. Images obtained following deposition onto mica from mixtures of DNA and the polyelectrolyte PFP-NR3 in acetonitrile...
Source: Biomacromolecules - October 8, 2009 Category: Biochemistry Authors: Davies ML, Burrows HD, Cheng S, Morán MC, Miguel MD, Douglas P Tags: Biomacromolecules Source Type: journals

Molecular Weight and Polydispersity of Calf-Thymus DNA: Static Light-Scattering and Size-Exclusion Chromatography with Dual Detection.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Plausible calf-thymus DNA molecular weight distribution can be obtained by size-exclusion chromatography with dual low-angle light scattering/refractometric detection at sufficiently low flow rate. The distribution extends over three decades of molecular weight and is characterized by weight average molecular weight M(w) = 8418000 and polydispersity index M(w)/M(n) = 5.2. After strongly scattering impurities had been removed from the sample using adsorption properties of the 3 mum mixed-cellulose-ester filter membranes, static light-scattering measurement in flow injection mode was feasible and gave M(w) = 8580000, cor...
Source: Biomacromolecules - October 8, 2009 Category: Biochemistry Authors: Porsch B, Laga R, Horský J, Koňák C, Ulbrich K Tags: Biomacromolecules Source Type: journals

Viscoelasticity and Phase Separation of Aqueous Na-Type Gellan Solution.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Viscoelastic and phase behaviors of Na-type gellan were investigated. The complex shear modulus of aqueous gellan solutions was monitored as a function of concentration, temperature, and molar mass. At relatively low concentrations, the loss shear modulus, G'', increased steeply at a certain temperature upon cooling, which was attributed to helix formation. Above a certain concentration, a steep increase and then gradual decrease of G'' was observed. The decrease of G'' was significant and is considered to be due to anisotropic phase formation, judging from the macroscopic phase separation into upper isotropic and lowe...
Source: Biomacromolecules - October 8, 2009 Category: Biochemistry Authors: Nitta Y, Takahashi R, Nishinari K Tags: Biomacromolecules Source Type: journals

Solid-State (13)C NMR Study of a Composite of Tobacco Xyloglucan and Gluconacetobacter xylinus Cellulose: Molecular Interactions between the Component Polysaccharides.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
To investigate possible molecular interactions between xyloglucans (XGs) and cellulose in plant cell walls, a model composite was produced using cellulose from the bacterium Gluconacetobacter xylinus and XG from the walls of a tobacco cell-suspension culture that had been incubated with (13)C-labeled glucose. Solid-state (13)C NMR with cross-polarization (CP) and magic-angle spinning (MAS) was used in combination with proton spin-relaxation editing to separate signals from crystalline (rigid) and less rigid domains of the composite. Signals from XG were confined to subspectra of less rigid domains, with no detectable s...
Source: Biomacromolecules - October 8, 2009 Category: Biochemistry Authors: Bootten TJ, Harris PJ, Melton LD, Newman RH Tags: Biomacromolecules Source Type: journals

Enzymatic One-Pot Route to Telechelic Polypentadecalactone Epoxide: Synthesis, UV Curing, and Characterization.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In an enzymatic one-pot procedure immobilized lipase B from Candida antarctica was used to synthesize semicrystalline diepoxy functional macromonomers based on glycidol, pentadecalactone, and adipic acid. By changing the stoichiometry of the building blocks, macromonomers of controlled molecular weight from 1400 to 2700 g mol(-1) could be afforded. The enzyme-catalyzed reaction went to completion (conversion >/=95%) within 24 h at 60 degrees C. After removal of the enzyme, the produced macromonomers were used for photopolymerization without any purification. The macromonomers readily copolymerized cationically with ...
Source: Biomacromolecules - October 6, 2009 Category: Biochemistry Authors: Eriksson M, Fogelström L, Hult K, Malmström E, Johansson M, Trey S, Martinelle M Tags: Biomacromolecules Source Type: journals

Synthesis and Characterization of Biodegradable Poly(ester amide)s with Pendant Amine Functional Groups and In Vitro Cellular Response.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The purpose of this study was to use a convenient synthetic strategy to prepare a new family of biodegradable amino acid-based poly(ester amide)s (PEAs) with pendant amine groups along the polymer backbone, and investigate the applications of the new polymers in the biomedical area. Two amino acids, l-phenylalanine (Phe) and l-lysine (Lys), were used as the model amino acid compounds to illustrate the synthesis, characterization, and biological property of this new family of functional PEAs. These new PEAs were obtained by two-step reactions, the ring-opening reaction of epsilon-(benzyloxycarbonyl)-l-lysine N-carboxyan...
Source: Biomacromolecules - October 6, 2009 Category: Biochemistry Authors: Deng M, Wu J, Reinhart-King CA, Chu CC Tags: Biomacromolecules Source Type: journals

Synthesis and Characterization of Hydroxyl-Functionalized Caprolactone Copolymers and Their Effect on Adhesion, Proliferation, and Differentiation of Human Mesenchymal Stem Cells.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study shows that the aforementioned hydrophilic polymers are attractive candidates for the design of scaffolds for tissue engineering applications. PMID: 19807059 [PubMed - as supplied by publisher] (Source: Biomacromolecules)
Source: Biomacromolecules - October 5, 2009 Category: Biochemistry Authors: Seyednejad H, Vermonden T, Fedorovich NE, van Eijk R, van Steenbergen MJ, Dhert WJ, van Nostrum CF, Hennink WE Tags: Biomacromolecules Source Type: journals

Structural Determinants of Antimicrobial Activity and Biocompatibility in Membrane-Disrupting Methacrylamide Random Copolymers.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Low molecular weight random copolymers bearing protonated primary amine groups and hydrophobic alkyl groups in the side chains were synthesized and their activities against E. coli , S. aureus , human red blood cells, and human epithelial carcinoma cells (HEp-2) were quantified. The mole fraction of alkyl side chains in the copolymers (f(alkyl)) and the length of the alkyl chains were major determinants of the activities. Against E. coli cells, activity was diminished as f(alkyl) was increased from 0 to about 0.2, but was then enhanced dramatically as f(alkyl) was increased further. Activity against S. aureus was dimin...
Source: Biomacromolecules - October 4, 2009 Category: Biochemistry Authors: Palermo EF, Sovadinova I, Kuroda K Tags: Biomacromolecules Source Type: journals

Optimized and Standardized Isolation and Structural Characterization of Anti-inflammatory Sulfated Polysaccharides from the Red Alga Delesseria sanguinea (Hudson) Lamouroux (Ceramiales, Delesseriaceae).Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In conclusion, SPs from Delesseria sanguinea can be isolated in reproducibly high quality by using a specific extraction procedure. Thus, an important prerequisite for a potential economical utilization is fulfilled. PMID: 19795906 [PubMed - as supplied by publisher] (Source: Biomacromolecules)
Source: Biomacromolecules - October 1, 2009 Category: Biochemistry Authors: Grünewald N, Alban S Tags: Biomacromolecules Source Type: journals

Foldable Antibacterial Acrylic Intraocular Lenses of High Refractive Index.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Hydrophilic copolymers with high refractive index and bactericide properties based on quaternary ammonium salts monomers and methacrylates bearing benzothiazole moieties have been developed for application as foldable intraocular lenses. Composition of the systems was adjusted to get materials with optimized flexibility, wettability, and refractive properties. All the materials have been characterized in terms of optical properties, glass transition temperature, water content, and wettability. Water contact values oscillated between 37 and 15% and refractive index values in the wet state between 1.49 and 1.53, dependin...
Source: Biomacromolecules - September 30, 2009 Category: Biochemistry Authors: Parra F, Vázquez B, Benito L, Barcenilla J, San Román J Tags: Biomacromolecules Source Type: journals

Synthesis and Characterization of Macroporous Thermosensitive Hydrogels from Recombinant Elastin-Like Polymers.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Multifunctional bioactive chemically cross-linked elastin-like polymers (ELPs) have been prepared as three-dimensional scaffolds for tissue engineering. The salt-leaching/gas-foaming technique was found suitable to prepare highly porous biodegradable hydrogels based on this novel material type. The porosity can be controlled by the amount of sodium hydrogen carbonate incorporated during the cross-linking reaction, whereas the mean pore size is determined by the salt particle size. The gas-foaming process, which involves immersion in a citric acid solution after the cross-linking, facilitates pore interconnectivity and ...
Source: Biomacromolecules - September 30, 2009 Category: Biochemistry Authors: Martín L, Alonso M, Girotti A, Arias FJ, Rodríguez-Cabello JC Tags: Biomacromolecules Source Type: journals

Computational Study of the Conformational Structures of Saccharides in Solution Based on J Couplings and the "Fast Sugar Structure Prediction Software"Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This article reports on the implementation of J coupling calculations in our recently developed Fast Sugar Structure Prediction Software (FSPS). The FSPS combines a smart and exhaustive algorithm to search through conformational space with the calculation of different experimental nuclear magnetic resonance observables to establish the conformation of saccharides in solution. Using our algorithm in combination with NMR data, we investigate the solution structure of three simple disaccharides (methyl alpha-sophoroside, methyl alpha-laminarabioside, and methyl alpha-cellobioside) and one complex bacterial polysaccharide ( Sh...
Source: Biomacromolecules - September 30, 2009 Category: Biochemistry Authors: Xia J, Margulis CJ Tags: Biomacromolecules Source Type: journals