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Synthetic Polymers (synthetic + polymer)
Selected AbstractsBioinspired Mineralization of Inorganics from Aqueous Media Controlled by Synthetic PolymersMACROMOLECULAR BIOSCIENCE, Issue 2 2007Katarzyna Gorna Abstract The formation of inorganic structures in nature is commonly controlled by biogenic macromolecules. The understanding of mineralization phenomena and the nucleation and growth mechanisms involved is still a challenge in science but also of great industrial interest. This article focuses on the formation and mineralization of two archetypical inorganic materials: zinc oxide and amorphous calcium carbonate (ACC). Zinc oxide is selected as a model compound to investigate the role that polymers play in mineralization. Most of the effort has been devoted to the investigation of the effects of double-hydrophilic block and graft copolymers. Recent work has demonstrated that latex particles synthesized by miniemulsion polymerization, properly functionalized by various chemical groups, have similar effects to conventional block copolymers and are excellently suited for morphology control of ZnO crystals. Latex particles might serve as analogues of natural proteins in biomineralization. The second example presented, ACC, addresses the issue of whether this amorphous phase is an intermediate in the biomineralization of calcite, vaterite, or aragonite. Conditions under which amorphous calcium carbonate can be obtained as nanometer-sized spheres as a consequence of a liquid,liquid phase segregation are presented. Addition of specific block copolymers allows control of the particle size from the micrometer to the submicrometer length scale. The physical properties of novel materials synthesized from concentrated solution and their potential applications as a filler of polymers are also discussed. [source] Liquid Chromatography of Synthetic Polymers under Limiting Conditions of Insolubility IIIMACROMOLECULAR SYMPOSIA, Issue 1 2007Application of Monolithic Columns Abstract Summary Performance was evaluated of silica based commercial monolithic rod-like columns in liquid chromatography of synthetic polymers under limiting conditions of enthalpic interactions (LC LC). LC LC employs the barrier effect of the pore permeating and therefore slowly eluting small molecules toward the pore excluded, fast eluting macromolecules. Phase separation (precipitation) barrier action was applied in present study. The barrier was created either by the narrow pulse of an appropriate nonsolvent injected into the column just before the sample solution (LC LC of insolubility , LC LCI) or by the eluent itself. In the latter case, the polymer sample was dissolved and injected in a good solvent (LC LC of solubility , LC LCS). In LC LCI, polymer species cannot break thru the nonsolvent zone while in LC LCS they cannot enter eluent, which is their precipitant. Therefore, polymer species keep moving in the zone of their original solvent. Macromolecules eluting under the LC LC mechanism leave the column in the retention volume (VR) roughly corresponding to VR of the low molar mass substances and can be efficiently separated from the polymer species non-hindered by the barrier action. The known advantages of monoliths were confirmed. From the point of view of LC LCI and LC LCS the most important quality of monolithic columns represents their excellent permeability, which allows both working at high flow rates and injecting very high (in the range of 5%) sample concentrations. Monolithic column tolerate also extremely high molar mass samples (M>10,000 kg,·,mol,1). On the other hand, the mesopores (separation pores) of the tested monoliths exhibited rather small volume and wide size distribution. These shortcomings partially impair the permeability advantage of monoliths because in order to obtain high LC LC separation selectivity a tandem of several monolithic columns must be applied. Presence of large mesopores also reduces applicability of monolithic columns for molar masses below about 50 kg,·,mol,1 because VRs of polymers eluted behind the barrier are similar to that of freely eluting species. The non- negligible break-thru phenomenon was observed for the very high polymer molar masses largely eluting behind the barrier. It is assumed that the fraction of very large mesopores present in the monoliths or association/microphase separation of macromolecules may be responsible for this phenomenon. This is why the presently marketed SiO2 monolithic columns are mainly suitable for the fast purification of the LC LC eluting macromolecules from the polymeric admixtures non-hindered by the barrier-forming liquid. Still, monolithic columns have large potential in the LC LCI and LC LCS procedures provided size (effective diameter) of the mesopores can be reduced and their volume increased. [source] Helix Formation in Synthetic Polymers by Hydrogen Bonding with Native Saccharides in Protic MediaCHEMISTRY - A EUROPEAN JOURNAL, Issue 30 2006Minoru Waki Abstract Water-soluble poly(m -ethynylpyridine)s were designed to realize saccharide recognition in protic media. UV/Vis, 1H NMR, and fluorescence measurements revealed that the polymer forms a helical higher order structure by solvophobic interactions between the ethynylpyridine units in the protic medium. The resulting pore in the helix behaves like a binding pocket in proteins, by taking advantage of inwardly directed hydrogen-bonding functional groups of the polymers. Molecular recognition of native saccharides by the polymers was investigated by circular dichroism (CD). The chirality of the saccharide was transferred to the helical sense of the polymers, accompanied by the appearance of induced CDs (ICDs) in the absorptive region of the polymers. In MeOH/water (10/1), mannose and allose showed intense ICDs, and the apparent association constant between the polymer and D -mannose was 14,M,1. [source] Biological,synthetic hybrid block copolymers: Combining the best from two worldsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2005Harm-Anton Klok Abstract Although biopolymers and synthetic polymers share many common features, each of these two classes of materials is also characterized by a distinct and very specific set of advantages and disadvantages. Combining biopolymer elements with synthetic polymers into a single macromolecular conjugate is an interesting strategy for synergetically merging the properties of the individual components and overcoming some of their limitations. This article focuses on a special class of biological,synthetic hybrids that are obtained by site-selective conjugation of a protein or peptide and a synthetic polymer. The first part of the article gives an overview of the different liquid-phase and solid-phase techniques that have been developed for the synthesis of well-defined, that is, site-selectively conjugated, synthetic polymer,protein hybrids. In the second part, the properties and potential applications of these materials are discussed. The conjugation of biological and synthetic macromolecules allows the modulation of protein binding and recognition properties and is a powerful strategy for mediating the self-assembly of synthetic polymers. Synthetic polymer,protein hybrids are already used as medicines and show significant promise for bioanalytical applications and bioseparations. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1,17, 2005 [source] Biodegradable Xylitol-Based Polymers,ADVANCED MATERIALS, Issue 10 2008Joost P. Bruggeman Synthetic polymers composed of metabolites endogenous to the mammalian organism are designed. The design is based on the monomer xylitol, which possesses a wide range of physical properties that are biologically relevant. Xylitol-based hydrogels and elastomers are biocompatible in vitro and in vivo, compared to the prevalent synthetic polymer poly(L-lactic- co - glycolic acid) (PLGA). It furthermore provides a platform to tune mechanical properties, degradation profiles, and cell attachment. [source] Synthetic polymers containing ,-amino acids: from polyamides to poly(ester amide)s,JOURNAL OF PEPTIDE SCIENCE, Issue 5 2005Jordi Puiggalí Abstract Polyamides and poly(ester amide)s which contain glycine residues as a comonomer show unique features. In collaboration with Professor M. Goodman we carried out studies on low molecular weight models which allow a structural analysis with atomic detail. In this way, sequential polyamides constituted by glycine and ,-amino acids may adopt new structures characterized by a network of intermolecular hydrogen bonds that are established along three directions at 120°. This peculiar structure is based on the conformational preferences of glycine residues. X-ray and electron microscopy studies on poly(ester amide)s indicate a structure constituted by a stacking of hydrogen bonded sheets. Differences have been found in the shift between consecutive sheets. Copyright © 2005 European Peptide Society and John Wiley & Sons, Ltd. [source] Bone morphogenetic proteins in tissue engineering: the road from laboratory to clinic, part II (BMP delivery)JOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE, Issue 2-3 2008P. C. Bessa Abstract Bone morphogenetic proteins (BMPs) are cytokines with a strong effect on bone and cartilage growth and with important roles during embryonic patterning and early skeletal formation. BMPs have promising potential for clinical bone and cartilage repair, working as powerful bone-inducing components in diverse tissue-engineering products. Synthetic polymers, natural origin polymers, inorganic materials and composites may be used as carriers for the delivery of BMPs. Carriers range from nanoparticles to complex three-dimensional (3D) scaffolds, membranes for tissue-guided regeneration, biomimetic surfaces and smart thermosensitive hydrogels. Current clinical uses include spinal fusion, healing of long bone defects and craniofacial and periodontal applications, amongst others. BMP-2 and BMP-7 have recently received approval by the US Food and Drug Administration (FDA) for specific clinical cases, delivered in absorbable collagen sponges. Considering the expanding number of publications in the field of BMPs, there are prospects of a brilliant future in the field of regenerative medicine of bone and cartilage with the use of BMPs. Copyright © 2008 John Wiley & Sons, Ltd. [source] Fire performance of wood (Pinus radiata) treated with fire retardants and a wood preservativeFIRE AND MATERIALS, Issue 6 2008D. C. O. Marney Abstract In this work, we co-formulated an oil-borne copper naphthenate/permethrin wood preservative system with synthetic polymer-based fire-retardant additives prior to the impregnation of Pinus radiata sapwood. We evaluated what effect, if any, the preservative had upon the fire performance properties of the fire retardants and whether the fire retardants impacted on the fungicidal and termiticidal efficacy of the preservative. The fire retardants included halogenated and phosphorus-based systems. A mass loss calorimeter, in conjunction with a thermopile, was used to measure the time to ignition and the peak heat release rate (PHRR) from which the fire performance index (FPI) was determined. The preservative properties were evaluated using termite and soil-block decay bioassays. In summary, we found that the rate of fire growth was reduced when the fire retardants were used in combination with the wood preservative. We also found that the PHRR was a better determinant of fire performance than the FPI. The performance of the wood preservative was enhanced against fungal decay and termite attack when used in combination with the fire retardants. The fire retardants also demonstrated some wood preservative properties of their own. Copyright © 2008 John Wiley & Sons, Ltd. [source] Repair of segmental defects in rabbit humeri with titanium fiber mesh cylinders containing recombinant human bone morphogenetic protein-2 (rhBMP-2) and a synthetic polymerJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2002Narumichi Murakami Abstract To develop a new technology that enhances the regeneration potential of bone and the repair of large intercalated defects in long bone, recombinant human bone morphogenetic protein-2 (BMP-2; 20 ,g or 40 ,g) was mixed in a polymer gel (poly-lactic acid-polyethyleneglycol block copolymer; PLA-PEG; 200 mg) and incorporated into titanium fiber-mesh cylinders. Three 5-mm cylinders were placed end-to-end to fill a 15-mm defect created in the humeri of adult rabbits and were stabilized by an intramedullary rod. In controls, the titanium fiber-mesh cylinders were combined with PLA-PEG in the absence of BMP. Six weeks after implantation, new bone had formed on the surface of the implant and had bridged the defect. All of the defects (5/5) treated by cylinders containing 120 ,g (40 ,g × 3) of BMP were repaired completely. New bone formation was also found inside the pores of the cylinders. The defect was not repaired in the control animals. These results demonstrate that these new composite implants fabricated by combining rhBMP, synthetic degradable polymers and compatible biomaterials enhance the regeneration potential of bone. Thus, it is possible that large skeletal defects can be repaired using this prosthesis in lieu of autogenous bone graft. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 62: 169,174, 2002 [source] Synthesis, characterization and hybridization studies of new nucleo-,-peptides based on diaminobutyric acidJOURNAL OF PEPTIDE SCIENCE, Issue 12 2006G. N. Roviello Abstract In the present work, we report the synthesis and the characterization of a new chiral nucleoaminoacid, in which a diaminobutyric moiety is connected to the DNA nucleobase by an amidic bond, and its oligomerization to give the corresponding nucleo-,-peptide. The ability of this synthetic polymer to bind complementary DNA was studied in order to explore its possible use in antigene/antisense or diagnostic applications. Our interest in the presented DNA analogue was also supported by the importance of ,-aminoacid-containing compounds in natural products of biological activity and by the known stability of ,-peptides to enzymatic degradation. Furthermore, our work could contribute to the study of the role of nucleopeptides as prebiotic material in a PNA world that could successively lead to the actual DNA/RNA/protein world, as recently assumed. Copyright © 2006 European Peptide Society and John Wiley & Sons, Ltd. [source] Characterization of amorphous solids with weak glass transitions using high ramp rate differential scanning calorimetryJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 2 2008Derrick S. Katayama Abstract Measurement of the glass transition temperature (Tg) of proteins and other high molecular weight polymers in the amorphous state is often difficult, since the transition is extremely weak, that is, the ,Cp at the glass transition temperature is small. For example, little is known about the solid-state properties of hydroxyethyl starch (HES), which is beginning to become more commonly evaluated as a bulking agent in pharmaceutical products. For weak thermal events, such as the change in heat capacity at the Tg of a pure protein or large synthetic polymer, increased heating rate should produce greater sensitivity in terms of heat flow. Recent innovations in rapid scanning technology for differential scanning calorimetry (DSC) allow measurements on materials where the thermal events are difficult to detect by conventional DSC. In the current study, measurements of the Tg of proteins in the solid state, amorphous pharmaceutical excipients which have small ,Cp at the glass transition temperature, and bacterial spores, have all been made using high ramp rate DSC, providing information on materials that was inaccessible using conventional DSC methods. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97:1013,1024, 2008 [source] Synthesis and characterization of synthetic polymer colloids colloidally stabilized by cationized starch oligomersJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 7 2009Marianne Gaborieau Abstract A method is developed for anchoring enzymatically degraded cationized starch as electrosteric stabilizers onto synthetic latices, using cerium(IV) to create free-radical grafting sites on the starch. Direct anchoring of debranched starch onto a poly(methyl methacrylate) seed latex yields a latex stabilized by well-defined oligosaccharides. Using ,-amylase to randomly cleave starch to form (1,4)-,-glucans, and a comonomer, N -isopropyl acrylamide (NIPAM), whose corresponding polymer exhibits a lower critical solution temperature (LCST), creates a means to synthesize block (or graft) oligomers of oligosaccharide and synthetic polymer, which are water soluble at room temperature. Above 30 °C, they become amphiphilic and form self-emulsifying nanoparticles (sometimes termed "frozen micelles") from which a synthetic latex is grown after addition of methyl methacrylate, the collapsed NIPAM-containing entities functioning as a type of in situ seed. This synthesis of stable synthetic latex particles is shown to have a high grafting efficiency. The starch fragments were characterized by 1H solution-state NMR before grafting, and 13C solid-state cross-polarization magic-angle spinning (CP-MAS) NMR was used to characterize the starch oligomers actually grafted on the final latex. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1836,1852, 2009 [source] Biological,synthetic hybrid block copolymers: Combining the best from two worldsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2005Harm-Anton Klok Abstract Although biopolymers and synthetic polymers share many common features, each of these two classes of materials is also characterized by a distinct and very specific set of advantages and disadvantages. Combining biopolymer elements with synthetic polymers into a single macromolecular conjugate is an interesting strategy for synergetically merging the properties of the individual components and overcoming some of their limitations. This article focuses on a special class of biological,synthetic hybrids that are obtained by site-selective conjugation of a protein or peptide and a synthetic polymer. The first part of the article gives an overview of the different liquid-phase and solid-phase techniques that have been developed for the synthesis of well-defined, that is, site-selectively conjugated, synthetic polymer,protein hybrids. In the second part, the properties and potential applications of these materials are discussed. The conjugation of biological and synthetic macromolecules allows the modulation of protein binding and recognition properties and is a powerful strategy for mediating the self-assembly of synthetic polymers. Synthetic polymer,protein hybrids are already used as medicines and show significant promise for bioanalytical applications and bioseparations. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1,17, 2005 [source] Comparison of HPLC enantioseparation of substituted binaphthyls on CD-, polysaccharide- and synthetic polymer-based chiral stationary phasesJOURNAL OF SEPARATION SCIENCE, JSS, Issue 9 2010Lucie Loukotková Abstract Retention and enantioseparation behavior of ten 2,2,-disubstituted or 2,3,2,-trisubstituted 1,1,-binaphthyls and 8,3,-disubstituted 1,2,-binaphthyls, which are used as catalysts in asymmetric synthesis, was investigated on eight chiral stationary phases (CSPs) based on ,-CD, polysaccharides (tris(3,5-dimethylphenylcarbamate) cellulose or amylose CSPs) and new synthetic polymers (trans -1,2-diamino-cyclohexane, trans -1,2-diphenylethylenediamine and trans -9,10-dihydro-9,10-ethanoanthracene-(11S,12S)-11,12-dicarboxylic acid CSPs). Normal-, reversed-phase and polar-organic separation modes were employed. The effect of the mobile phase composition was examined. The enantiomeric separation of binaphthyl derivatives, which possess quite similar structures, was possible in different enantioselective environments. The substituents and their positions on the binaphthyl skeleton affect their properties and, as a consequence, the separation system suitable for their enantioseparation. In general, the presence of ionizable groups on the binaphthyl skeleton, substitution with non-identical groups and a chiral axis in the 1,2, position had the greatest impact on the enantiomeric discrimination. The 8,3,-disubstituted 1,2,-binaphthyl derivatives were the most easily separated compounds in several separation systems. From all the chiral stationary phases tested, cellulose-based columns were shown to be the most convenient for enantioseparation of the studied analytes. However, the polymeric CSPs with their complementary behavior provided good enantioselective environments for some derivatives that could be hardly separated in any other chromatographic system. [source] Synthesis and Controlled Polymerisation of a Novel Gramicidin S AnalogueMACROMOLECULAR RAPID COMMUNICATIONS, Issue 16 2005Lee Ayres Abstract Summary: The controlled polymerisation of a bulky, peptide-based monomer was investigated. The cyclic , -sheet forming decapeptide gramicidin S was modified with a methacrylate handle and subsequently polymerised via atom transfer radical polymerisation (ATRP), to yield a well-defined gramicidin-S-containing polymer. The secondary structure of the peptide moiety was retained within the resulting polymer, as indicated by IR spectroscopy. This is the first example of the use of ATRP to create a synthetic polymer with a cyclic peptide as a side chain. The gramicidin S based monomers synthesised here were then polymerised by ATRP. [source] Helical polyacetylene,Origins and synthesisTHE CHEMICAL RECORD, Issue 6 2008Kazuo Akagi Abstract We present the origins and synthesis of helical polyacetylene (H-PA) by focusing on its peculiar spiral morphology. Interfacial polymerization of acetylene was carried out in an asymmetric reaction field consisting of chiral nematic liquid crystal (N*-LC) and Ziegler,Natta catalyst. As the N*-LC is composed of nematic liquid crystal and a chiral compound such as a binaphthyl derivative with either the R - or S -configuration, the screw directions of the polyacetylene chain and fibril bundle,and even the spiral morphology,are rigorously controlled by the chirality of the selected compound. Interestingly, the screw directions of the fibril and the bundle in H-PA were found to be opposite to that of N*-LC. It is worthwhile to emphasize that the hierarchical spiral morphology involving the primary to higher order structure is generated in a synthetic polymer such as polyacetylene by using N*-LC as an asymmetric polymerization solvent. © 2008 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 8: 395,406; 2008: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20163 [source] A practical interface for microfluidics and nanoelectrospray mass spectrometryELECTROPHORESIS, Issue 9 2008Sergio L. S. Freire Abstract We report a new method for fabricating nanospray ionization tips for MS, formed from glass substrates and the inert polymer, parylene-C. Using a single photolithography step, the emitters are formed contiguously with microchannels, such that no dead volumes are observed. In addition, because the devices are very thin (,0.3,mm) and the tips are formed at rectangular corners, the Taylor cone volumes are small, which makes the method attractive for future integration with microfluidic separations. Device performance was demonstrated by evaluating diverse analytes, ranging from synthetic polymers, to peptides, to nucleic acids. For all analytes, performance was similar to that of conventional emitters (pulled-glass capillaries and the Agilent HPLC ChipÔ) with the advantage of rapid, batch fabrication of identical devices. [source] Molecularly imprinted polymers as a tool for separation in CECELECTROPHORESIS, Issue 1-2 2007Zhao-Sheng Liu Dr. Abstract Molecularly imprinted polymers (MIPs) are synthesized in the presence of a template which results in the formation of specific recognition cavities complementary to the template in shape and chemical functionality. One of the most successful application areas of MIPs is chromatographic sorbents, which are tailor-made synthetic polymers for a given analyte. However, low efficiency of MIP columns is often observed because of slow kinetics of the template. CEC-based MIPs are thought to improve efficiency of MIP-based separation due to the enhanced flow dynamics of CEC. Another attractive feature is the miniaturized format of CEC, so that fewer templates or monomers for the molecular imprinting are consumed, a characteristic desired for ,green chemistry'. The small dimensions of a capillary demand the development of novel polymer formats that can be applied to a miniaturized system. This review discusses the various formats, i.e., the micro- or nanoparticle, the coating and the monolith, for application in CEC as well as the use in MIP syntheses and characteristics. [source] Proteolytically Degradable Photo-Polymerized Hydrogels Made From PEG,Fibrinogen Adducts,ADVANCED ENGINEERING MATERIALS, Issue 6 2010Daniel Dikovsky Abstract We develop a biomaterial based on protein,polymer conjugates where poly(ethylene glycol) (PEG) polymer chains are covalently linked to multiple thiols on denatured fibrinogen. We hypothesize that conjugation of large diacrylate-functionalized linear PEG chains to fibrinogen could govern the molecular architecture of the polymer network via a unique protein,polymer interaction. The hypothesis is explored using carefully designed shear rheometry and swelling experiments of the hydrogels and their precursor PEG/fibrinogen conjugate solutions. The physical properties of non-cross-linked and UV cross-linked PEGylated fibrinogen having PEG molecular weights ranging from 10 to 20,kDa are specifically investigated. Attaching multiple hydrophilic, functionalized PEG chains to the denatured fibrinogen solubilizes the denatured protein and enables a rapid free-radical polymerization cross-linking reaction in the hydrogel precursor solution. As expected, the conjugated protein-polymer macromolecular complexes act to mediate the interactions between radicals and unsaturated bonds during the free-radical polymerization reaction, when compared to control PEG hydrogels. Accordingly, the cross-linking kinetics and stiffness of the cross-linked hydrogel are highly influenced by the protein,polymer conjugate architecture and molecular entanglements arising from hydrophobic/hydrophilic interactions and steric hindrances. The proteolytic degradation products of the protein,polymer conjugates proves to be were different from those of the non-conjugated denatured protein degradation products, indicating that steric hindrances may alter the proteolytic susceptibility of the PEG,protein adduct. A more complete understanding of the molecular complexities associated with this type of protein-polymer conjugation can help to identify the full potential of a biomaterial that combines the advantages of synthetic polymers and bioactive proteins. [source] A Fibronectin Peptide-Coupled Biopolymer Nanofibrous Matrix to Speed Up Initial Cellular EventsADVANCED ENGINEERING MATERIALS, Issue 4 2010Ji-Eun Kim Degradable polymer nanofibers produced by electrospinning are attractive for use in cell culture and tissue repair. However, the hydrophobicity and initial poor cell adhesion of synthetic polymers have limited their use in tissue regeneration. Herein, the surface of a poly(lactide-co-caprolactone) Arg-Gly-Asp sequence of nanofiber was tailored with a fibronectin peptide (FN10), which was designed to retain the central cell-binding domain. The electrospun nanofibers are first treated with an alkaline solution to reveal the carboxyl groups on the surface, which is followed by coupling with an FN10 solution in conjunction with a carbodiimide-based agent. Peptide coupling occurs effectively with saturation within 1,h, and the coupled peptide maintains its stability for several days. The peptide-coupled nanofibers show significant improvements in initial cell adhesion and spreading compared with the untreated one, confirming the role of the FN10 peptide in the initial cell events. This methodology may be useful in tailoring the surface of polymeric nanofibers with biomolecules targeted for specific tissue responses. [source] Calcite-specific coupling protein in barnacle underwater cementFEBS JOURNAL, Issue 24 2007Youichi Mori The barnacle relies for its attachment to underwater foreign substrata on the formation of a multiprotein complex called cement. The 20 kDa cement protein is a component of Megabalanus rosa cement, although its specific function in underwater attachment has not, until now, been known. The recombinant form of the protein expressed in bacteria was purified in soluble form under physiological conditions, and confirmed to retain almost the same structure as that of the native protein. Both the protein from the adhesive layer of the barnacle and the recombinant protein were characterized. This revealed that abundant Cys residues, which accounted for 17% of the total residues, were in the intramolecular disulfide form, and were essential for the proper folding of the monomeric protein structure. The recombinant protein was adsorbed to calcite and metal oxides in seawater, but not to glass and synthetic polymers. The adsorption isotherm for adsorption to calcite fitted the Langmuir model well, indicating that the protein is a calcite-specific adsorbent. An evaluation of the distribution of the molecular size in solution by analytical ultracentrifugation indicated that the recombinant protein exists as a monomer in 100 mm to 1 m NaCl solution; thus, the protein acts as a monomer when interacting with the calcite surface. cDNA encoding a homologous protein was isolated from Balanus albicostatus, and its derived amino acid sequence was compared with that from M. rosa. Calcite is the major constituent in both the shell of barnacle base and the periphery, which is also a possible target for the cement, due to the gregarious nature of the organisms. The specificity of the protein for calcite may be related to the fact that calcite is the most frequent material attached by the cement. [source] Mussel-Inspired Polydopamine Coating as a Universal Route to Hydroxyapatite CrystallizationADVANCED FUNCTIONAL MATERIALS, Issue 13 2010Jungki Ryu Abstract Bone tissue is a complex biocomposite material with a variety of organic (e.g., proteins, cells) and inorganic (e.g., hydroxyapatite crystals) components hierarchically organized with nano/microscale precision. Based on the understanding of such hierarchical organization of bone tissue and its unique mechanical properties, efforts are being made to mimic these organic,inorganic hybrid biocomposites. A key factor for the successful designing of complex, hybrid biomaterials is the facilitation and control of adhesion at the interfaces, as many current synthetic biomaterials are inert, lacking interfacial bioactivity. In this regard, researchers have focused on controlling the interface by surface modifications, but the development of a simple, unified way to biofunctionalize diverse organic and inorganic materials remains a critical challenge. Here, a universal biomineralization route, called polydopamine-assisted hydroxyapatite formation (pHAF), that can be applied to virtually any type and morphology of scaffold materials is demonstrated. Inspired by the adhesion mechanism of mussels, the pHAF method can readily integrate hydroxyapatites on ceramics, noble metals, semiconductors, and synthetic polymers, irrespective of their size and morphology (e.g., porosity and shape). Surface-anchored catecholamine moieties in polydopamine enriches the interface with calcium ions, facilitating the formation of hydroxyapatite crystals that are aligned to the c -axes, parallel to the polydopamine layer as observed in natural hydroxyapatites in mineralized tissues. This universal surface biomineralization can be an innovative foundation for future tissue engineering. [source] Natural-Synthetic Polyblend Nanofibers for Biomedical ApplicationsADVANCED MATERIALS, Issue 27 2009Narayan Bhattarai The ability to produce well-blended nanofibers from natural and synthetic polymers represents a significant advancement in development of composite materials with desired structures and material properties. The nanofiber presented here exhibits excellent structural stability and mechanical and biological properties favorable for biomedical applications, and offers a new nanofibrous platform for development of matrices for various biomedical applications. [source] Tandem mass spectrometry of synthetic polymersJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 9 2009Anna C. Crecelius Abstract The detailed characterization of macromolecules plays an important role for synthetic chemists to define and specify the structure and properties of the successfully synthesized polymers. The search for new characterization techniques for polymers is essential for the continuation of the development of improved synthesis methods. The application of tandem mass spectrometry for the detailed characterization of synthetic polymers using the soft ionization techniques matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) and electrospray ionization mass spectrometry (ESI-MS), which became the basic tools in proteomics, has greatly been increased in recent years and is summarized in this perspective. Examples of a variety of homopolymers, such as poly(methyl methacrylate), poly(ethylene glycol), as well as copolymers, e.g. copolyesters, are given. The advanced mass spectrometric techniques described in this review will presumably become one of the basic tools in polymer chemistry in the near future. Copyright © 2009 John Wiley & Sons, Ltd. [source] New strategies for polymer development in pharmaceutical science , a short reviewJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 9 2001A. Godwin We are developing synthetic polymers for pharmaceutical and medical applications. These applications can be broadly grouped on how the polymer will be utilized e.g. material, excipient or molecule. Our focus is to develop polymers with more defined structures that are based on biological, physicochemical and/or materials criteria. Strategies are being developed to more efficiently optimize structure,property correlations during preclinical development. We describe two examples of our research on pharmaceutical polymer development: narrow molecular weight distribution (MWD) homopolymeric precursors which can be functionalized to give families of narrow MWD homo- and co-polymers, and hydrolytically degradable polymers. [source] Development of synthetic double helical polymers and oligomersJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 20 2009Yoshio Furusho Abstract There is growing interest in the design and synthesis of artificial helical polymers and oligomers, in connection with biological importance as well as development of novel chiral materials. Since the discovery of the helical structure of isotactic polypropylene, a significant advancement has been achieved for synthetic polymers and oligomers with a single helical conformation for about half a century. In contrast, the chemistry of double helical counterparts is still premature. This short review highlights the recent advances in the synthesis, structures, and functions of double helical polymers and oligomers, featuring an important role of supramolecular chemistry in the design and synthesis of double helices. Although the artificial double helices reported to date are still limited in number, recent advancement of supramolecular chemistry provides plenty of structural motifs for new designs. Therefore, artificial double helices hold great promise as a new class of compounds. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5195,5207, 2009 [source] Biological,synthetic hybrid block copolymers: Combining the best from two worldsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2005Harm-Anton Klok Abstract Although biopolymers and synthetic polymers share many common features, each of these two classes of materials is also characterized by a distinct and very specific set of advantages and disadvantages. Combining biopolymer elements with synthetic polymers into a single macromolecular conjugate is an interesting strategy for synergetically merging the properties of the individual components and overcoming some of their limitations. This article focuses on a special class of biological,synthetic hybrids that are obtained by site-selective conjugation of a protein or peptide and a synthetic polymer. The first part of the article gives an overview of the different liquid-phase and solid-phase techniques that have been developed for the synthesis of well-defined, that is, site-selectively conjugated, synthetic polymer,protein hybrids. In the second part, the properties and potential applications of these materials are discussed. The conjugation of biological and synthetic macromolecules allows the modulation of protein binding and recognition properties and is a powerful strategy for mediating the self-assembly of synthetic polymers. Synthetic polymer,protein hybrids are already used as medicines and show significant promise for bioanalytical applications and bioseparations. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1,17, 2005 [source] Comparison of HPLC enantioseparation of substituted binaphthyls on CD-, polysaccharide- and synthetic polymer-based chiral stationary phasesJOURNAL OF SEPARATION SCIENCE, JSS, Issue 9 2010Lucie Loukotková Abstract Retention and enantioseparation behavior of ten 2,2,-disubstituted or 2,3,2,-trisubstituted 1,1,-binaphthyls and 8,3,-disubstituted 1,2,-binaphthyls, which are used as catalysts in asymmetric synthesis, was investigated on eight chiral stationary phases (CSPs) based on ,-CD, polysaccharides (tris(3,5-dimethylphenylcarbamate) cellulose or amylose CSPs) and new synthetic polymers (trans -1,2-diamino-cyclohexane, trans -1,2-diphenylethylenediamine and trans -9,10-dihydro-9,10-ethanoanthracene-(11S,12S)-11,12-dicarboxylic acid CSPs). Normal-, reversed-phase and polar-organic separation modes were employed. The effect of the mobile phase composition was examined. The enantiomeric separation of binaphthyl derivatives, which possess quite similar structures, was possible in different enantioselective environments. The substituents and their positions on the binaphthyl skeleton affect their properties and, as a consequence, the separation system suitable for their enantioseparation. In general, the presence of ionizable groups on the binaphthyl skeleton, substitution with non-identical groups and a chiral axis in the 1,2, position had the greatest impact on the enantiomeric discrimination. The 8,3,-disubstituted 1,2,-binaphthyl derivatives were the most easily separated compounds in several separation systems. From all the chiral stationary phases tested, cellulose-based columns were shown to be the most convenient for enantioseparation of the studied analytes. However, the polymeric CSPs with their complementary behavior provided good enantioselective environments for some derivatives that could be hardly separated in any other chromatographic system. [source] A composite material model for improved bone formationJOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE, Issue 7 2010Silvia Scaglione Abstract The combination of synthetic polymers and calcium phosphates represent an improvement in the development of scaffolds for bone-tissue regeneration. Ideally, these composites provide both mechanically and architecturally enhanced performances; however, they often lack properties such as osteoconductivity and cell bioactivation. In this study we attempted to generate a composite bone substitute maximizing the available osteoconductive surface for cell adhesion and activity. Highly porous scaffolds were prepared through a particulate leaching method, combining poly-,-caprolactone (PCL) and hydroxyapatite (HA) particles, previously coated with a sucrose layer, to minimize their embedding by the polymer solution. Composite performances were evaluated both in vitro and in vivo. In PCL,sucrose-coated HA samples, the HA particles were almost completely exposed and physically distinct from the polymer mesh, while uncoated control samples showed ceramic granules massively covered by the polymer. In vivo results revealed a significant extent of bone deposition around all sucrose-coated HA granules, while only parts of the control uncoated HA granules were surrounded by bone matrix. These findings highlight the possibility of generating enhanced osteoconductive materials, basing the scaffold design on physiological and cellular concepts. Copyright © 2010 John Wiley & Sons, Ltd. [source] State of the art and future directions of scaffold-based bone engineering from a biomaterials perspectiveJOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE, Issue 4 2007Dietmar Werner Hutmacher Abstract Scaffold-based bone tissue engineering aims to repair/regenerate bone defects. Such a treatment concept involves seeding autologous osteogenic cells throughout a biodegradable scaffold to create a scaffold,cell hybrid that may be called a tissue-engineered construct (TEC). A variety of materials and scaffolding fabrication techniques for bone tissue engineering have been investigated over the past two decades. This review aims to discuss the advances in bone engineering from a scaffold material point of view. In the first part the reader is introduced to the basic principles of bone engineering. The important properties of the biomaterials and the scaffold design in the making of tissue engineered bone constructs are discussed in detail, with special emphasis placed on the new material developments, namely composites made of synthetic polymers and calcium phosphates. Advantages and limitations of these materials are analysed along with various architectural parameters of scaffolds important for bone tissue engineering, e.g. porosity, pore size, interconnectivity and pore-wall microstructures. Copyright © 2007 John Wiley & Sons, Ltd. [source] | |||||||||||||||||||||||||||||||