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Wet-spinning of polymeric materials has been widely investigated for various biomedical applications, such as extracorporeal blood treatment, controlled drug release and tissue engineering. This review is aimed at summarizing and assessing current advances in wet-spinning of biomedical polymers to manufacture single fibres and three-dimensional scaffolds, as well as their functionalization through loading with bioactive agents. The theoretical principles and the main technological aspects of fibre production by wet-spinning on either a laboratory or an industrial scale are outlined. The non-solvent-induced phase inversion determining polymer coagulation during the wet-spinning process is discussed by highlighting its influence on the resulting fibre morphology and how it can be exploited to induce a nano/microporosity in the solidified polymeric matrix. The versatility of wet-spinning in material selection, bioactive agent loading and fibre morphology tuning is underlined through an overview of significant literature reporting on the processing of various naturally derived and synthetic polymers. A special focus is given to cutting-edge advancements in the application of additive manufacturing principles to wet-spinning for enhanced control and reproducibility of three-dimensional polymeric scaffold morphology at different scale levels (i.e. macrostructural to micro/nanostructural features). © 2017 Society of Chemical Industry

This chapter presents an overview of the current knowledge on experimental methods for monitoring the biodegradability of polymeric materials. The focus is, in particular, on the biodegradation of materials under environmental conditions. Examples of in vivo degradation of polymers used in biomedical applications are not covered in detail but have been extensively reviewed elsewhere, e.g., [1 – 3] . Nevertheless, it is good to realize that the same principles of the methods for monitoring biodegradability of environmental polymers are also used for the evaluation of the degradation behavior of biomedical polymers. A number of different aspects of assessing the potential, the rate, and the degree of biodegradation of polymeric materials are discussed. The mechanisms of polymer degradation and erosion receive attention and factors affecting enzymatic and nonenzymatic degradation are briefl y addressed. Particular attention is given to the various ways for measuring biodegradation, including complete mineralization to gasses (such as carbon dioxide and methane), water, and possibly microbial biomass. Finally, some general conclusions are presented with respect to measuring biodegradability of polymeric materials.

Water uptake influences many properties of polymers and has been widely studied. In the context of polymeric biomaterials, several publications reported an unusual high variability of analytical results, without further investigating the cause for this phenomenon. Using selected polymers from the library of L-tyrosine-derived polyarylates and poly(D,L lactic acid), we showed that nonaged and nonannealed compression molded film samples exhibit the typical large variation in water uptake observed in previous reports. The introduction of an annealing step allows accurate and reproducible water uptake measurements for these polymers. We evaluated the use of 3H-radiolabeled water for the determination of water uptake, finding that the use of radiolabeled water yields statistically indistinguishable measurements, compared to gravimetric methods, while providing significant advantages in throughput and sensitivity. Using the recommended methods of annealing and 3H-radiolabled water, the water uptake profiles of 24 polymers of the library of L-tyrosine-derived polyarylates are reported. This article addresses experimental concerns related to water uptake studies and may assist other researchers in improving the accuracy of their water uptake results. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

A recently developed electrohydrodynamic printing method is described that can be used to create ordered structures and complex patterns using coarse processing needles and two polymeric materials. The results highlight the method's potential for direct 3D writing of biomedical polymers and composites for a variety of biomedical applications.

The nature of plasma-induced surface radicals formed on a variety of organic polymers have been studied by electron spin resonance (ESR), making it possible to provide a sound basis for future experimental design of polymer surface processing using plasma treatment. On the basis of the findings from such studies, several novel bio-applications in the field of drug- and biomedical- engineering have been developed. Applications for drug engineering include the preparation of reservoir-type drug delivery system (DDS) of sustained- and delayed-release, and floating drug delivery system (FDDS) possessing gastric retention capabilities, followed by preparation of "Patient-Tailored DDS". Furthermore, the preparation of composite powders applicable to matrix-type DDS was developed by making a mechanical application to the surface radical-containing polymer powders with drug powders. In applications for biomedical engineering, the novel method to introduce the durable surface hydrophilicity and lubricity on hydrophobic biomedical polymers was developed by plasma-assisted immobilization of carboxyl group-containing polymer on the polymer substrate. The surfaces thus prepared were further used for the covalent immobilization of oligo-nucleotides (DNA) onto the polymer surfaces applicable to constructing DNA diagnosis system, and also plasma-assisted preparation of functionalized chemo-embolic agent of vinyl alcohol-sodium acrylate copolymer (PVA- PAANa).

Poly(lactic-co-glycolic) acid (PLGA) is one of the most versatile biomedical polymers, already approved by regulatory authorities to be used in human research and clinics. Due to its valuable characteristics, PLGA can be tailored to acquire desirable features for control bioactive payload or scaffold matrix. Moreover, its chemical modification with other polymers or bioconjugation with molecules may render PLGA with functional properties that make it the Holy Grail among the synthetic polymers to be applied in the biomedical field. In this review, the physical-chemical properties of PLGA, its synthesis, degradation, and conjugation with other polymers or molecules are revised in detail, as well as its applications in drug delivery and regeneration fields. A particular focus is given to successful examples of products already on the market or at the late stages of trials, reinforcing the potential of this polymer in the biomedical field.

Hydrogels were the first biomaterials designed for clinical use. Their discovery and applications as soft contact lenses and implants are presented. This early hydrogel research served as a foundation for the expansion of biomedical polymers research into new directions: design of stimuli sensitive hydrogels that abruptly change their properties upon application of an external stimulus (pH, temperature, solvent, electrical field, biorecognition) and hydrogels as carriers for the delivery of drugs, peptides, and proteins. Finally, pathways to self-assembly of block and graft copolymers into hydrogels of precise 3D structures are introduced.

8 páginas, 6 figuras, 2 esuqemas, 4 tablas., Bioresorbable linear poly(ester-ether urethane)s with different hydrophilic character were synthesized from block copolymers of poly(ϵ-caprolactone)-poly(ethylene oxide)-poly(ϵ-caprolactone) (PCL-PEO-PCL) as macrodiols, and L-lysine diisocyanate (LDI). A series of PCL-PEO-PCL triblock copolymers with different PEO and PCL chain length was obtained by reacting PEO with ϵ-caprolactone. Polyurethanes were synthesized by reacting the triblock copolymers with LDI in solution using stannous 2-ethylhexanoate as catalyst. The prepared triblock copolymers and polyurethanes were fully characterized by proton nuclear magnetic resonance spectroscopy, size exclusion chromatography, differential scanning calorimetry, and wide-angle X-ray diffraction. Water uptake, hydrolytic stability, and tensile properties of polyurethanes with different composition were evaluated and discussed in terms of the chain length and molecular weight of the polymers and its block components. Water uptake seems to depend on the ethylene oxide unit content of the polyurethane regardless of the triblock structure. Mechanical properties of the synthesized polymers were strongly affected by the molecular weight achieved during polymerization. The use of triblock macrodiols with different hydrophilicity allowed the preparation of a series of polyurethanes having a broad range of properties., The donation of LDI from Kyowa Hakko Kogyo Co. Ltd (Japan), the partial support of MAT2001/1634 project, Fundación ANTORCHAS and CONICET (Argentina) are gratefully acknowledged.

Surface modification of biomedical polymers by the technique of surface grafting was briefly overviewed, mostly based on our results. It was shown that surface grafting of water-soluble polymer chains onto polymeric biomaterials was effective in producing mechanically non-stimulative, blood-compatible, antibacterial, tissue-bonding, and cell-adhesive surfaces. In addition to the improvement of the interfacial biocompatibility, the surface grafting was useful also for obtaining a biofunctional surface such as immunoadsorbent.

Polymers are ubiquitous components of products manufactured for medical and pharmaceutical applications. Widely used commodity polymers were the first polymers to be utilised in biomedical applications. These polymers were not developed with biocompatibility established at the onset and many speciality polymers have been developed in recent years to begin to meet the multifaceted demands for medical development, the optimisation of structure-property correlations and ultimately, clinical use. In the broader area of materials research, combinatorial or high throughput strategies used for drug development are recognised to have potential for discovery and process development. Much of the application of combinatorial chemistry in drugs research has been dependent on the use of polymeric reagents, substrates and supports. The chemistry of the reactions on polymers in solid and liquid phases have also played a major role in combinatorial drugs research. There is considerable interest in combinatorial materials research and this review outlines how this research may be applied for biomedical polymer development.

Studies utilizing a quantitative assay, radioimmunoassay, and a biological activity assay, the murine thymocyte proliferation assay, to analyze IL-1 beta cytokine production by monocytes/macrophages on biomedical polymers have been carried out. Results indicate that the quantitative analysis of IL-1 beta on biomedical polymers and protein-adsorbed biomedical polymers is not indicative of and does not correlate with the results of the biological activity assay. IL-1 beta secreted from human monocytes/macrophages on Biomer, polydimethylsiloxane (PDMS), Dacron, polyethylene, expanded polytetrafluoroethylene, and control polystyrene with and without the preadsorption of physiological concentrations of human IgG, fibrinogen, and/or fibronectin was assayed. Quantitative levels of IL-1 beta suggest a greater functional response than that observed in the biological thymocyte proliferation assay when the polymers were studied directly or preadsorbed with IgG. On the other hand, preadsorption with fibrinogen or fibronectin resulted in high functional activity for IL-1 beta with low quantitative levels of IL-1 beta. The lack of correlation between the functional and biological activity assays suggests the presence of other cytokines or antagonists which modulate the biological activity of IL-1 beta.

Addition reactions of diethylamine onto 1,4-divinylbenzene (DVB) catalyzed by lithium diethylamide were examined to find a synthetic route to a group of new monomers possessing dialkylamino substituents, which is expected to be a starting material for biomedical polymers such as ionic polymer complexes, polycations, and others. It was found that 1-(2-diethylaminoethyl)-4-vinylbenzene (1) and 1,4-bis(2-diethylaminoethyl)-benzene (2) can be prepared selectively, because the rate of the first step of the addition reaction was twenty times as large as that of the second step. Results of kinetic studies on the addition reactions towards DVB are discussed with the aid of 13C NMR data and compared with other p-vinylbenzene derivatives. Das Ziel der Arbeit galt der Synthese einer neuen Gruppe von Monomeren mit Dialkylaminosubstituenten, die als Ausgangsmaterial fur pharmakologisch aktive Polymere (Polymerkomplexe, Polycationen u. a.) dienen konnte. Die neuen Monomeren wurden durch Lithium-diathylamid katalysierte Additionsreaktionen von Diathylamin an 1,4-Divinylbenzol (DVB) hergestellt. 1-(2-Diathylaminoathyl)-4-vinylbenzol (1) und 1,4-Bis(2-diathylaminoathyl)benzol (2) liesen sich dabei getrennt erhalten, weil die Geschwindigkeit des ersten Additionsschrittes etwa 20mal groser ist als diejenige des zweiten. Die Ergebnisse der kinetischen Untersuchungen der Additionsreaktionen an DVB wurden mit dessen 13C NMR Spektren in Beziehung gebracht und mit den Daten anderer p-Vinylbenzolderivate verglichen.

Le polyacide β-maleique semble etre le polymere fonctionnel le plus attirant pour elaborer des polymeres «prodrug»

In vitro cell culture techniques were used to evaluate the effect of several clinically significant biomedical polymers on monocyte activation and Interleukin 1 (IL1) production. Isolated human peripheral blood monocytes were cultured in the presence of a panel of five biomedical polymers routinely used in a variety of clinical applications: Polyethylene (PE), silica-free poly-dimethylsiloxane (PDMS), woven Dacron fabric, expanded polytetrafluoroethylene (ePTFE) and the segmented polyurethane, Biomer. Monocytes generated IL1 in the presence of all five materials. Maximal levels of IL1 were generated at 24 h in monocyte-polymer cultures supplemented with serum and additionally stimulated with lipopolysaccharide (LPS). No difference was observed due to serum source. Results from cultures supplemented with fetal bovine serum were not significantly different from those obtained with human serum supplemented cultures. The thymocyte proliferative activity generated by monocytes in the presence of these biomedical polymers was neutralized by a specific polyclonal anti-IL1 antiserum. Statistically significant differences in IL1 production were observed between polymers, allowing their classification according to reactivity into high (Dacron, PE), intermediate (ePTFE) and low (Biomer, PDMS) reactive groups.