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Despite the rapid progress of several three-dimensional (3D) printing technologies, there exists a critical barrier in-term of processability of high performance materials. Polyether-ether-ketone (PEEK) is known for its higher mechanical properties, chemical stability, biological stability and biocompatibility suitable for certain biomedical applications. Examining a growing body of scientific literature on 3D printing of biomedical polymers indicates that most of the studies are conducted using biomedical polymers such as poly-carpolactone, poly-lactic acid, poly-glycolic acid, polyethylene and polyurethanes. However, studies on 3D Printing of PEEK is sparse owing to the higher temperatures needed for melting, lacking of availability of suitable feedstock, concerns over poor adhesion between layers, and time consuming and uneconomical processing steps. Given the unique nature of PEEK class of polymers, this manuscript closely examines 3D printability of PEEK for a range of biomedical applications. This manuscript also presents ideas, feasible solutions and enabling scientific mechanisms to improve the 3D printability of PEEK. This article will help the research community to strengthen the conceptual knowledge and insights on the 3D printing of PEEK based medical devices and tools, and future possibilities.

Near-field electrospinning (NFES) and melt electrowriting (MEW) are the process of extruding a fiber due to the force exerted by an electric field and collecting the fiber before bending instabilities occur. When paired with precise relative motion between the polymer source and the collector, a fiber can be directly written as dictated by preprogrammed geometry. As a result, this precise fiber control results in another dimension of scaffold tailorability for biomedical applications. In this review, biomedically relevant polymers that to date have manufactured fibers by NFES/MEW are explored and the present limitations in direct fiber writing of standardization in published setup details, fiber write throughput, and increased ease in the creation of complex scaffold geometries are discussed.

[EN] We aimed to study the distribution of hydroxyapatite (HA) and halloysite nanotubes (HNTs) as fillers and their influence on the hydrophobic character of conventional polymers used in the biomedical field. The hydrophobic polyester poly (¿-caprolactone) (PCL) was blended with its more hydrophilic counterpart poly (lactic acid) (PLA) and the hydrophilic acrylate poly (2-hydroxyethyl methacrylate) (PHEMA) was analogously compared to poly (ethyl methacrylate) (PEMA) and its copolymer. The addition of HA and HNTs clearly improve surface wettability in neat samples (PCL and PHEMA), but not that of the corresponding binary blends. Energy-dispersive X-ray spectroscopy mapping analyses show a homogenous distribution of HA with appropriate Ca/P ratios between 1.3 and 2, even on samples that were incubated for seven days in simulated body fluid, with the exception of PHEMA, which is excessively hydrophilic to promote the deposition of salts on its surface. HNTs promote large aggregates on more hydrophilic polymers. The degradation process of the biodegradable polyester PCL blended with PLA, and the addition of HA and HNTs, provide hydrophilic units and decrease the overall crystallinity of PCL. Consequently, after 12 weeks of incubation in phosphate buffered saline the mass loss increases up to 48% and mechanical properties decrease above 60% compared with the PCL/PLA blend., Dominguez-Candela thanks the Universitat Politècnica de València for the financial support through an FPI-UPV grant (PAID-01-19)

Fast growing applications of 3D printing still lacked with a hurdle of printing high functional executing polymers. Poly-ether-ether-ketone (PEEK) produces excellent mechanical properties, chemical stability, biological stability and biocompatibility, especially employable for clinical applications. Previous literature is on fabrication of biomedical polymers by additive manufacturing (AM) such as poly-carpolactone, poly-lactic acid, poly-glycolic acid, poly-ethylene and polyurethanes. Only few studies are conducted on 3D printing of PEEK is due to its high melting point, non-availability of feed stock and poor properties of printed parts. This present review paper concentrates on printing of porous architecture which will be suitable for various medical applications with the use of the PEEK material.

Although biodegradable polymers were widely researched, this is the first study considering the effect of combined testing environments and cyclic loading on the most important aspect related to additive manufacturing: the interfacial bond between deposited layers. Its results give confidence in applicability of the material extrusion additive manufacturing technology for biomedical fields, by demonstrating that the interface behaves in a manner similar to that of the bulk-polymer material. To do this, especially designed tensile specimens were used to analyse the degradation of 3D-printed polymers subjected to constant-amplitude and incremental cyclic loads when tested in air at room temperature (control) and submerged at 37 °C (close to in-vivo conditions). The mechanical properties of the interface between extruded filaments were compared against the bulk material, i.e. along filaments. In both cases, cyclic loading caused only a negligible detrimental effect compared to non-cyclic loading (less than 10 % difference in ultimate tensile strength), demonstrating the suitability of using 3D-printed components in biomedical applications, usually exposed to cyclic loading. For cyclic tests with a constant loading amplitude, larger residual deformation (>100 % greater) and energy dissipation (>15 % greater) were found when testing submerged in solution at 37 °C as opposed to in laboratory conditions (air at room temperature), as used by many studies. This difference may be due to plasticisation effects of water and temperature. For cyclic tests with incrementally increasing loading amplitudes, the vast majority of energy dissipation happened in the last two cycles prior to failure, when the polymer approached the yield point. The results demonstrate the importance of using an appropriate methodology for biomedical applications; otherwise, mechanical properties may be overestimated.

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

Several new classes of polymeric materials are being introduced with unique properties. Thermoresponsive polymers (TRPs) are one of the most fascinating and emerging class of biomaterials in biomedical research. The design of TRPs with good response to temperature and its ability to exhibit coil to globular transition behavior near to physiological temperature made them more promising materials in the field of biomaterials and biomedicines. Instead of numerous studies on TRPs, the mechanistic interplay among several additives and TRPs is still not understood clearly and completely. The lack of complete understanding of biomolecular interactions of various additives with TRPs is limiting their applications in interdisciplinary science as well as pharmaceutical industry. There is a great need to provide a collective and comprehensive information of various additives and their behavior on widely accepted biopolymers, TRPs such as poly(N-isopropylacrylamide) (PNIPAM), poly(vinyl methyl ether) (PVME), poly(N-vinylcaprolactum) (PVCL) and poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol) (PEG-PPG-PEG) in aqueous solution. Obviously, as the literature on the influence of various additives on TRPs is very vast, therefore we focus our review only on these four selected TRPs. Additives such as polyols, methylamines, surfactants and denaturants basically made the significant changes in water structure associated to polymer via their entropy variation which is the direct influence of their directly or indirectly binding abilities. Eventually, this review addresses a brief overview of the most recent literature of applications based phase behavior of four selected TRPs in response to external stimuli. The work enhances the knowledge for use of TRPs in the advanced development of drug delivery system and in many more pharmaceutical applications. These kinds of studies provide powerful impact in exploring the utility range of polymeric materials in various field of science.

Polymeric materials are widely used in orthopedics and traumatology where they have an irreplaceable role in the construction of implants. Unlike metals and ceramics, polymers have a low elastic modulus close to that of cortical bone. Bulk properties together with surface, chemical, and biological properties play a crucial role with regards to the biomedical polymers. However, due to the variability of the polymeric implant applications, the large amount of different polymer types, the variability of their properties and chemistry and, last but not least, many possible methods of their treatment to reach or improve the demanded properties, the polymers used in implant applications are a complex and complicated topic. Plasma surface treatment methods provide independent modification possibilities to the surface and biological properties without any alteration or degradation to the bulk (mechanical) properties. The required biological, chemical, and surface properties of the polymer-based implants will be briefly described including an overview of the plasma methods for the surface treatment of polymeric materials. Afterwards, we will also focus on plasma-modified polymer implants used in various medical applications.

Polylactide (PLA) represents one of the most promising biomedical polymers due to its biodegradability, bioresorbability and good biocompatibility. This work highlights the synthesis and characterization of PLAs using novel diethylzinc/gallic acid (ZnEt2/GAc) and diethylzinc/propyl gallate (ZnEt2/PGAc) catalytic systems that are safe for human body. The results of the ring-opening polymerization (ROP) of rac-lactide (rac-LA) in the presence of zinc-based catalytic systems have shown that, depending on the reaction conditions, “predominantly isotactic”, disyndiotactic or atactic PLA can be obtained. Therefore, the controlled and stereoselective ROP of rac-LA is discussed in detail in this paper.

The appropriate anti-adhesive effect of polymers on cells or tissues in the body is one of the essential requirements of maintaining health and protecting the body from trauma and foreign bodies. Regulating the anti-adhesive properties of biomedical polymers against cells has been considered a pivotal parameter in developing polymeric biomaterials for biomedical applications such as artificial blood vessels and cell encapsulation. Meanwhile, tissue adhesion barriers that can physically isolate wounds and thus effectively prevent the formation of tissue adhesion have been a hot topic in both research and industrial fields. This review describes the comprehensive knowledge and recent research efforts on polymers for anti-adhesion to both cells and tissues. The basic concepts and mechanisms for the design and performance of anti-adhesive polymers are introduced in terms of both cell and tissue. Polymer-based approaches for anti-adhesion to cells or tissues are then extensively discussed.

Polymeric biomaterials have significant impact in the aged society. Biocompatible and biodegradable polymers have emerged during the past decades to promise extraordinary breakthroughs in a wide range of diagnostic and therapeutic medical devices. Understanding and controlling the interfacial interactions of the polymeric biomaterials with biological elements, such as water, ions, proteins, bacteria, fungai and cells, are essential toward their successful implementation in biomedical applications. Here we highlight the recent developments of biocompatible and biodegradable fusion polymeric biomaterials for medical devices and provide an overview of the recent progress of the design of the multi-functional biomedical polymers by controlling bio-interfacial water structure through precision polymer synthesis and supramolecular chemistry. Biocompatible and biodegradable polymers have emerged during the past decades to promise extraordinary breakthroughs in a wide range of diagnostic and therapeutic medical devices. Understanding and controlling the interfacial interactions of the polymeric biomaterials with biological elements are of essential towards their successful implementation in biomedical applications. Here, we highlight recent developments of biocompatible and biodegradable fusion polymeric biomaterials for medical devices and overview of the recent progress of the design of the multi-functional biomedical polymers by controlling biointerfacial water structure through precision polymer synthesis and supramolecular chemistry.

To evaluate the effects of ionic liquids (ILs) on the microstructural features of aliphatic polyesters for biomedical applications, a series of copolymers were synthesized by lipase ring opening polymerization of rac-lactide (rac-LA) and ε-caprolactone (CL). The chemical structures of resulting polymers were characterized by 1H- and 13C-NMR and the average molecular weight (Mn) and dispersity index were characterized by gel permeation chromatography. The structure of the copolymers confirms the presence of linear polymer chains with end-functional hydroxyl groups allowing covalent coupling of the therapeutic agents. Chain microstructure of copolymers indicates the presence of both random and block copolymers depending on the synthesis conditions. Moreover, it was found that CL is the most active co-monomer during copolymerization which enhances the polymerizability of rac-LA and allows to obtain higher Mn of the copolymers. The results demonstrate that ILs could be promising solvents in synthesis of aliphatic esters for biomedical applications.

Bio-based polymer hybrid composites hold a unique position in the fast-growing and active multidisciplinary world of biomaterials where engineers, scientists, and biologists combine their knowledge. It is well known that advances in science and engineering of biomaterials are crucial to solve complex medical and biomedical problems involving replacement, repair, and regeneration of tissues. This chapter covers the definition, importance, categorization, and application of polymer hybrid composites in the biomedical field. It is presented into two main parts. The first part includes the categorization of biomedical polymer hybrid composites, with information about the compositions and specifications of nanocomposites on the basis of hybridization of polymers with natural polymers, biopolymers, minerals, and metals. The second covers biomedical uses of polymer hybrid composites, considering their applications (i.e., drug delivery, tissue engineering, bioadhesion, etc.), and composition.

Background: Although various types of materials have been used widely in dialyzers, most biomaterials lack the desired functional properties to interface with blood and have not been engineered for optimum performance. Therefore, there is increasing demand to develop novel materials to address such problems in the dialysis arena. Numerous parameters of polymeric biomaterials can affect biocompatibility in a controlled manner. The mechanisms responsible for the biocompatibility of polymers at the molecular level have not been clearly demonstrated, although many theoretical and experimental efforts have been made to try and understand them. Moreover, water interactions have been recognized as fundamental for the blood response to contact with polymers. Summary: We have proposed the ‘intermediate water' concept and hypothesized that intermediate water, which prevents the proteins and blood cells from directly contacting the polymer surface, or nonfreezing water on the polymer surface, plays an important role in the biocompatibility of polymers. This chapter provides an overview of the recent experimental progress of biocompatible polymers measured by thermal, spectroscopic, and surface force techniques. Additionally, it highlights recent developments in the use of biocompatible polymeric biomaterials for dialyzers and provides an overview of the progress made in the design of multifunctional biomedical polymers by controlling the biointerfacial water structure through precision polymer synthesis. Key Messages: Intermediate water was found only in hydrated biopolymers (proteins, polysaccharides, and nucleic acids, DNA and RNA) and hydrated biocompatible synthetic polymers. Intermediate water could be one of the main screening factors for the design of appropriate dialyzer materials.

Polymers prepared by chemical vapor deposition (CVD) polymerization have found broad acceptance in research and industrial applications. However, their intrinsic lack of degradability has limited wider applicability in many areas, such as biomedical devices or regenerative medicine. Herein, we demonstrate, for the first time, a backbone-degradable polymer directly synthesized via CVD. The CVD co-polymerization of [2.2]para-cyclophanes with cyclic ketene acetals, specifically 5,6-benzo-2-methylene-1,3-dioxepane (BMDO), results in well-defined, hydrolytically degradable polymers, as confirmed by FTIR spectroscopy and ellipsometry. The degradation kinetics are dependent on the ratio of ketene acetals to [2.2]para-cyclophanes as well as the hydrophobicity of the films. These coatings address an unmet need in the biomedical polymer field, as they provide access to a wide range of reactive polymer coatings that combine interfacial multifunctionality with degradability.

Functional aliphatic polycarbonates have attracted significant attention as materials for use as biomedical polymers in recent years. The incorporation of pendent functionality offers a facile method of modifying materials postpolymerization, thus enabling functionalities not compatible with ring-opening polymerization (ROP) to be introduced into the polymer. In particular, polycarbonates bearing alkene-terminated functional groups have generated considerable interest as a result of their ease of synthesis, and the wide range of materials that can be obtained by performing simple postpolymerization modifications on this functionality, for example, through radical thiol-ene addition, Michael addition, and epoxidation reactions. This review presents an in-depth appraisal of the methods used to modify alkene-functional polycarbonates postpolymerization, and the diversity of practical applications for which these materials and their derivatives have been used.

Significant advances in the field of polymer science over the past century have resulted in synthetic polymers becoming the basis for many new approaches to medical therapies and in particular development of new medical devices. While natural polymers have long been used in medicine and surgery, their application in medical devices has experienced a renaissance with advances in understanding of polymer synthesis and processing. In this chapter, natural polymers are discussed in detail, with a focus on proteins and polysaccharides. The major advantages and disadvantages in relation to use of natural polymers are considered with an emphasis on the key factors impacting their biological performance in tissue contacting devices. Approaches to developing hybrid materials that combine the advantages of both natural and synthetic polymers are becoming increasingly topical and hold much promise for the future of medical devices that can integrate with and drive regeneration of tissues.

Polymers are the most multifaceted class of biomaterials that are routinely being used for biomedical applications ranging from surgical sutures to tissue engineering scaffolds, medical implants, and drug-eluting devices.

One of the reasons that polymers are important in biomedical applications is the ease with which they can be processed in comparison with metals and ceramics. Well-established methods practiced in the plastics industry for processing commodity and engineering polymers can be used to fabricate biomedical devices and scaffolds. Methods are also being developed to accommodate the special characteristics of biomedical polymers, such as for instance processing of degradable polymers that require additional precautions. Degradable polymers require water free environment, mild thermal processing conditions, and precise temperature controls. Solvent based processing is therefore preferred to avoid degradation and to incorporate drug and bioactives.

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

Synthetic polymer hydrogels constitute a group of materials, used in numerous biomedical disciplines, and are still developing for new promising applications. The aim of this study is to review information about well known and the newest hydrogels, show the importance of water uptake and cross-linking type and classify them in accordance with their chemical structure. Синтетичні полімерні гідрогелі являють собою групу біоматеріалів, які вже використовуються в чисельних біомедичних галузях, і які розробляються для нового перспективного застосування. В роботі проаналізовано інформацію як про відомі, так і новітні гідрогелі. Показано, наскільки важливими є здатність до водопоглинання і тип структурування, а також проведено класифікацію гідрогелів відповідно до їх хімічної структури.

The synthesis of the aliphatic polyesters — polylactide (PLA) and poly (e-caprolactanes) (PCL) in the ring-opening polymerization of cyclic esters in the presence tin(II) 2-ethylhexanoate (SnOct 2 ) has been presented. The obtained products were subjected to multiple purification procedures to remove residual organo-tin catalyst (Tables 2 and 3). The tin content in the polyesters was then determined by Electrothermal Atomic Absorption Spectroscopy (ET-AAS) (Tables 3 and 4) after each purification process. The results of the analysis were discussed taking into consideration the requirements placed by the European Pharmacopoeia regarding the amount of tin allowed in aliphatic biomedical polyesters. It was confirmed, that a four-stage purification of the polyreaction product led to a three-fold decrease in the concentration of tin to a level less than the value required by Pharmacopoeia for materials designated for contact with blood. Moreover, the purification process did not generate any degradation of the polymer.

Dense CO2 can be used as an environmentally-benign polymer processing medium because of its liquid-like densities and gas-like mass transfer properties.In this work, polymer bio-blends of polycarbonate (PC), a biocompatible polymer, and polycaprolactone (PCL), a biodegradable polymer were prepared. Dense CO2 was used as a reaction medium for the melt-phase PC polymerization in the presence of dense CO2-swollen PCL particles and this method was used to prepare porous PC/PCL blends. To extend the applicability of dense CO2 to the biomedical industry and polymer blend processing, the impregnation of ibuprofen into the blend was conducted and subsequent dissolution characteristics were observed.

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.

Biomedical polymer-silicate nanocomposites have potential to become critically important to the development of biomedical applications, ranging from diagnostic and therapeutic devices, tissue regeneration and drug delivery matrixes to various bio-technologies that are inspired by biology but have only indirect biomedical relation. The fundamental understanding of polymer-nanoparticle interactions is absolutely necessary to control structure-property relationships of materials that need to work within the chemical, physical and biological constraints required by an application. This review summarizes the most recent published strategies to design and develop polymer-silicate nanocomposites (including clay based silicate nanoparticles and bioactive glass nanoparticles) for a variety of biomedical applications. Emerging trends in bio-technological and biomedical nanocomposites are highlighted and potential new fields of applications are examined.

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.

In order to investigate poly(N-vinyl pyrrolidone) as an alternative to poly(ethylene glycol) in preparing a biomedical polymer, we synthesized a series of reverse thermogelling poly(N-vinyl pyrroli...

Intelligent polymers or stimuli-responsive polymers may exhibit distinct transitions in physical-chemical properties, including conformation, polarity, phase structure and chemical composition in response to changes in environmental stimuli. Due to their unique ‘intelligent’ characteristics, stimuli-sensitive polymers have found a wide variety of applications in biomedical and nanotechnological fields. This review focuses on the recent developments in biomedical application of intelligent polymer systems, such as intelligent hydrogel systems, intelligent drug delivery systems and intelligent molecular recognition systems. Also, the possible future directions for the application of these intelligent polymer systems in the biomedical field are presented.

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.

The aim of this study was to coat bioactive glass 13-93 fibres with biomedical polymers. Two methods were used to coat the fibres, namely, dipping and pulling through a viscous solution. With both methods the fibres were successfully coated. Dipping was preferred for thin fibres (20–50 μm) and with this method approximately 2–5 μm thin polymer coat was obtained on the fibre surface. Pulling through viscous solution was preferred for thicker fibres (150–250 μm) and with this method approximately 10–30 μm polymeric coat was obtained. Coating the fibres enables further processing of the bioactive glass fibres and improves the mechanical properties and processibility of fibres.

Impressive advances in biotechnology, bioengineering, and biomaterials with unique properties have led to increased interest in polymers and other novel materials in biological and biomedical research and development over the past two decades. Although biomaterials have already made an enormous impact in biomedical research and clinical practice, there is a need for better understanding of the surface and interfacial chemistry between tissue (or cells) and biomedical materials. This is because the detailed physicochemical events related to the biological response to the surface of materials still often remain obscure, even though surface properties are important determinants of biomedical material function. In this regard, data available in the literature show the complexity of the interactions (surface reorganization, non-specific/specific protein adsorption, and chemical reactions such as acid-base, ion pairing, ion exchange, hydrogen bonding, divalent-ion bridging) and the interrelationship between biological environments, interfacial properties, and surface functional groups responsible for the biological responses. Because of the multidisciplinary nature of surface and interfacial phenomena at the surface of biomedical polymers, this review focuses on several aspects of current work published on poly(alpha-hydroxy acid)s and their associated copolymers:surface structure-biomedical function relationships;physicochemical strategies for surface modification; and, finally,synthetic strategies to increase biocompatibility for specific in-vivo and/or in-vitro biomedical applications.

Biodegradable or bioresorbable polymers are commonly used in various pharmaceutical fields (e.g., as drug delivery systems, therapeutic systems or macromolecular drug conjugates). Polyesters are an important class of polymers widely utilized in pharmacy due to their biodegradability and biocompatibility features. In recent years, there has been increased interest in enzyme-catalyzed ring-opening polymerization (e-ROP) of cyclic esters as an alternative method of preparation of biodegradable or bioresorbable polymers. Ionic liquids (ILs) have been presented as green solvents in enzymatic ring-opening polymerization. The activity, stability, selectivity of enzymes in ILs and the ability to catalyze polyester synthesis under these conditions are discussed. Overall, the review demonstrates that e-ROP of lactones or lactides could be an effective method for the synthesis of useful biomedical polymers.

Blood compatible polymers are important in creating artificial organs and biomedical devices which can be used clinically more safely and effectively. The molecular design of the novel blood compatible polymers is carried out with attention to create a biomembrane-mimicking surface on biomedical devices. Polymers with phospholipid polar groups, 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer was prepared by radical polymerization of the MPC with other hydrophobic methacrylate. The MPC polymer constructed a biomembrane-like surface when they contacted with plasma, because of their strong affinity to natural phospholipids. The surface could suppress protein adsorption and subsequent platelet adhesion and activation. That means the MPC polymers have the potential for improving the blood compatibility of the biomedical devices. The application of the MPC polymers to modify the biomedical devices is also discussed.

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.

Recently, particular interest of scientists has been focused on biomedical polymers, especially those used for drug delivery systems, therapeutic systems and macromolecular prodrugs. The aforementioned applications have opened new exciting prospects for medicine, because specially designed polymers are capable of delivering medicinal substances to the target diseased tissues and cells together with dosing those drugs according to controlled specified pharmacodynamics. Particular attention has recently been paid to chemistry of biocompatiable and biodegradable polymers, because they have an advantage of being readily hydrolyzed into removable and non-toxic products, which can be subsequently eliminated by metabolic pathways. Furthermore, the biomedical polymers have to be synthesized now using friendly for the environment and safe for human health, effective natural initiators, co-initiators and/or catalysts.

The chemical and biochemical degradation and calcification are investigated as processes that alter the physical and mechanical properties of implanted polymers. The principles of oxidative, hydrolytic and enzymatic degradation and calcification of polymers in the body are discussed and the natural ageing of polymers in vivo and in vitro and the accelerated ageing of polymers are examined. The use of accelerated ageng is described as a method to predict changes in the physical and mechanical properties of polymers in vivo .

Dendrimers represent a class of novel polymers having unique molecular architectures characterized by their well-defined structure, with a high degree of molecular uniformity, low polydispersity and properties that make them attractive materials for the development of nanomedicines. The dendrimer drug delivery can be achieved by coupling a drug through one of two approaches. Hydrophobic drugs can be complexed within the hydrophobic dendrimer interior to make them water-soluble or drugs can be covalently coupled onto the surface of the dendrimer. In addition, dendrimers have been shown to be capable of bypassing efflux transporters. A new generation of dendrimer-based delivery systems will enable the efficient transport of drugs across cellular barriers. This review deals principally with the synthesis, characterization and recent applications of dendrimers. In future it will only ever be possible to designate a dendrimer as safe means of drug delivery related to a specific application. However, so far limited clinical experience using dendrimers makes it impossible to designate any particular system which is safe and non toxic. Although there is widespread concern as to the safety of nanosized particles, preclinical and clinical experience gained during the development of polymeric excipients, biomedical polymers and polymer therapeutics showed that judicious development of dendrimer chemistry for each specific application will ensure development of safe and important materials for biomedical and pharmaceutical use.

The nature of plasma-induced surface radicals formed on a variety of organic polymers has 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).

To protect electronic micro systems for medical devices speciality implants towards influences of aggressive environment and to reduce the electrochemical migration are used biomedical encapsulation materials. To research the polymers resistance during electrochemical migration was proposed the method of investigation of surface insulation resistance (SIR) of comb-electrode. The capture system consists of a common method of resistance's measuring. Investigated samples were covered with two different biomedical polymers a) Poly-Para-Xylylen of type PARYLENE C and b) silicone rubber of type MED 6–6606 and were contacted to artificial blood plasma, liquor and 0.9 % NaCl solution each in a tub. Continuously direct voltage +10 V was applied to samples. Measured data were detected every 10 minutes during first hour, every 1 hour during first 12 hours and every 12 hours during 30 days. Alteration of surface insulation resistance from time into different liquids was received and topography of samples was studied.

Nanofibers have been of great interest in the recent years, because of its huge potential to diverse fields, especially in biomedical applications. The most favorable feature is the dimension of nanofibers that resembles that of the natural collagen fibrils in nano scale. They thus provide extremely large surface area to volume ratio as compared to microfibers. Electrospinning is the most preferred method in producing nanofibers from polymers. In this chapter, an overview of polymer nanofibers is stated, specifically focusing on the electrospun nanofibers used in biomedical applications. Along with a brief description of history, principle, and operating parameters of electrospinning process, examples of specific functionalities are introduced through bulk and surface modifications of nanofibers. In addition, a broad range of biomedical application includes tissue-engineered scaffolds, wound dressings, medical device and implants, controlled drug release, and other applications in biosensor, biocatalyst, and bioenzyme. With the rapidly growing demand nanofibers should find its enormous potential for the future development of nanoscience and biomedicine.

We have tested the hypothesis that cell adhesion and spreading on polymer films are influenced by the amount of time that the polymer films are pre-aged in cell culture medium. Cell adhesion and spreading were assessed after a 6-h culture on poly(D,L-lactic acid) (PDLLA) films that had been pre-aged in cell culture medium for 30 min, 1, 3 or 7 d. Cell adhesion and spread area were enhanced as the duration of pre-aging PDLLA films in cell culture medium was increased. Materials characterization showed that the hydrophobicity and surface morphology of the PDLLA films changed with increasing length of pre-aging time. These results suggest that cell adhesion and spreading are sensitive to the time-dependent changes in PDLLA hydrophobicity and surface morphology that occur during exposure of the polymer to cell medium for different lengths of time. These results demonstrate that cell response to a degradable, biomedical polymer can change as a function of the amount of time that the polymer is exposed to physiological medium.

14 páginas, 10 figuras, 7 tablas., Non-toxic biodegradable linear poly(ester-urethane-urea)s with different hydrophilic character were synthesized from poly(ε-caprolactone) as macrodiol, l-lysine diisocyanate (LDI) and ethyl ester l-lysine or l-ornithine as chain extenders. Linear segmented polymers were synthesized by the prepolymer method with a tertiary amine playing a critical role in the chain extension in heterogeneous conditions. The prepared segmented polymers were fully chemically and physically characterized, including water uptake and hydrolytic stability measurements. Depending on the poly(ε-caprolactone) length, the segmented polymers were amorphous or semicrystalline. The crystallinity degree strongly affected the mechanical properties and water uptake behaviour., Partial financial support of this work by CICYT (MAT2004- 01654), CSIC and CONICET (2004AR0061), Fundación ANTORCHAS and ANPCyT is gratefully acknowledged. The donation of LDI by Kyowa Hakko Kogyo Co., Ltd (Japan) is acknowledged.

Atomic force microscopy (AFM) has become established as a powerful and versatile tool for investigating local mechanical properties. In addition, through the AFM tip–sample interaction, it has become possible to study the effects of perturbations and modifications to the surface of soft samples, such as polymers. The accurate knowledge of their response to continuous AFM scanning could help to design new materials having desirable mechanical properties. In this paper, we present the results obtained by applying a new methodology to investigate wear properties on two different type of polymer, poly(methyl-methacrylate) and poly(l-lactic acid). These polymers have been widely employed in biomedical applications and have recently been considered as good candidates for coronary metallic stent coatings. Copyright © 2006 John Wiley & Sons, Ltd.

Publisher Summary This chapter focuses on the polymers that are biocompatible, that is, those that are not toxic to the body on implantation, can be classified as being bioinert or bioresorbable. Generally, high molecular weight biocompatible polymers are non-degradable and are classed as bioinert. Toxicity can occur with normally biocompatible polymers due to leaching of low molecular weight plasticizers and additives. It is important to characterize the grade of polymer in use. What is sold as polymer X by one manufacturer may be very different from polymer X sold by another, due to the purity and additives present. Surface reactions and absorption of proteins at the polymer surface can also cause problems. Therefore, the surface texture and the shape of the implant are also important. Bioinert polymers, such as polyethylene and polymethylmethacrylate are used in joint replacements and are designed to remain in place, unchanged for many years. Polyethylene has been used in composites such as HAPEX®;, which has been used as middle ear prostheses. Polyesters, such as polyglycolic and polylactic acids, are used as resorbable polymers in applications, such as dissolving sutures. Resorbable polymers are also being investigated for use as scaffolds for tissue engineering applications.

The design of biorecognizable biomedical polymers has to be based on a sound biological rationale. Using this rationale, the principles of the design, synthesis, and characterization of biorecognizable polymers are demonstrated on several examples including: targetable water-soluble carriers of bioactive compounds, the relationship between the supramolecular structure of polymer conjugates and their biorecognition, poly(ethylene glycol) conjugates, bioadhesive polymers for colon-specific drug delivery, and biodegradable hydrogels.