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Polyether ether ketone (PEEK) has been widely used in the medical engineering due to its high strength to weight ratio, creep and wear-resistance, and anti-allergically properties. Grinding is generally used to produce PEEK parts with high accuracy and surface quality requirements. In this research, the tool loading and the effect of cryogenic cooling in the grinding of PEEK are studied for the first time. It is shown that the generated heat in the grinding process, which is mainly influenced by the tool micro-topography, process parameter, and coolant lubricant has an important role in the surface integrity of PEEK. Additionally, the influence of specific material removal rate and the dressing speed ratio on the specific grinding energy of PEEK was studied. The input parameters of the grinding process that are investigated in this study include cutting speed (vs), depth of cut (ae), and feed rate (vft). To investigate the grinding wheel topography, the effects of dressing overlap ratio (Ud) and the dressing speed ratio (qd) were also investigated. Grinding force, surface roughness, and loading of the grinding wheel were considered as output parameters. The experiments were designed based on response surface methodology and the optimum cutting condition was obtained based on this method. The depth of cut and the dressing overlap ratio had respectively the maximum and minimum impact on the surface roughness and cutting forces. Additionally, the tool loading was mainly influenced by the cutting speed.

Biomedical polymers face rigid requirements for the biocompatibility of their monomers, the final polymeric product, and their residual reagents from their synthesis schemes. However, their prepara...

Femtosecond laser micromachining is a hot topic in the field of micromachining. Femtosecond laser processing of biomacromolecular micro devices has a promising application prospect. The research content of this paper is femtosecond laser micromachining of biomacromolecule materials, aiming at exploring the mechanism of femtosecond laser micromachining. In this paper, the principle of the interaction between laser and polymer materials is briefly expounded, and the photophysical processes such as transition, energy conversion, energy transfer and electron transfer are explained from the molecular orbital, and the mechanism is classified as photothermal and photochemical action, which is manifested as accelerating material's relaxation transformation process and degradation process. The interaction between polymer materials and laser starts from molecules absorbing the energy of photons to complete the transition from ground state to excited state. Different modes of excitation state inactivation correspond to the conversion of light energy into light energy, heat energy or chemical energy. On the one hand, the thermal action leads to the viscoelastic transformation of the material, and the material deforms or flows under the thermoelastic action; on the other hand, the thermal action accelerates the degradation reaction of the polymer material. The carbonyl group on the molecular chain of PMMA and PLA is more likely to reach the excited state, and the chemical properties of the carbonyl excited state determine that the photochemical processes of PMMA and PLA concentrate on the carbonyl group.

Poly (l-lactic acid) (PLLA) is a promising biomedical polymer material with a wide range of applications. The diverse enantiomeric forms of PLLA provide great opportunities for thermal and mechanical enhancement through stereocomplex formation. The addition of poly (d-lactic acid) (PDLA) as a nucleation agent and the formation of stereocomplex crystallization (SC) have been proven to be an effective method to improve the crystallization and mechanical properties of the PLLA. In this study, PLLA was blended with different amounts of PDLA through a melt blending process and their properties were calculated. The effect of the PDLA on the crystallization behavior, thermal, and mechanical properties of PLLA were investigated systematically by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), polarized optical microscopy (POM), dynamic mechanical analysis (DMA), and tensile test. Based on our findings, SC formed easily when PDLA content was increased, and acts as nucleation sites. Both SC and homo crystals (HC) were observed in the PLLA/PDLA blends. As the content of PDLA increased, the degree of crystallization increased, and the mechanical strength also increased.

In a large number of medical devices, a key feature of a biomaterial is the ability to successfully bond to living tissues by means of engineered mechanisms such as the enhancement of biomineralization on a bone tissue engineering scaffold or the mimicking of the natural structure of the extracellular matrix (ECM). This ability is commonly referred to as "bioactivity". Materials sciences started to grow interest in it since the development of bioactive glasses by Larry Hench five decades ago. As the main goal in applications of biomedical devices and tissue scaffolds is to obtain a seamless tissue-material interface, achieving optimal bioactivity is essential for the success of most biomaterial-based tissue replacement and regenerative approaches. Polymers derived from lactic acid are largely adopted in the biomedical field, they are versatile, FDA approved and relatively cost-effective. However, as for many other widespread biomedical polymers, they are hydrophobic and lack the intrinsic ability of positively interacting with surrounding tissues. In the last decades scientists have studied many solutions to exploit the positive characteristics of polylactide-based materials overcoming this bottleneck at the same time. The efforts of this research fruitfully produced many effective tissue engineering technologies based on PLA and related biopolymers. This review aims to give an overview on the latest and most promising strategies to improve the bioactivity of lactic acid-based materials, especially focusing on biomolecule-free bulk approaches such as blending, copolymerization or composite fabrication. Avenues for future research to tackle current needs in the field are identified and discussed.

Water-soluble, biodegradable, nonionic, and biocompatible polymers with multiple functional groups are highly desired for biomedical applications. Here, we report that water-soluble nonionic poly(d/l-serine) is chirality-controllable, biodegradation-controllable, and non-cytotoxic. Hence, it can be a highly sought-after alternative to the widely used poly(ethylene glycol), with an additional advantage of having multiple hydroxyl groups for further functionalization. As one example of its biomedical applications, poly(d/l-serine) demonstrated an obvious cryoprotective effect on the red blood cells. The usage of poly(d/l-serine) in the cryopreservation field would be of great promise to resolve the difficulties in separating cryoprotectants due to toxicity.

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.

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.

A multitude of differently composed biomedical polymers has been researched for many years for their distinctive ease of production and wide range of applications. New technologies and new material characteristics have always evolved accordingly. The lumina of biomedical polymer tubes such as catheters, intravenous tubes, and biomedical microfluidic channels do not necessarily show the required biocompatibility and desired functionality. In such cases, the products are provided with additional inner liner or coatings to achieve the desired specific properties. Specific adjustments, for example, low friction coefficient, low gas diffusion resistance, wear resistance, and hydrophobicity, are key properties which are in focus for the improvement of biomedical surfaces. In this pilot study, a technical method was developed to deposit parylene-AF4 on the inner surface of silicone tubes with aspect ratios exceeding 78:1. Uncoated and parylene-AF4-coated silicone tubes were investigated in respect to the aforementioned physical properties. Compared to the uncoated tubes, the parylene-coated tubes showed superior quality with respect to friction coefficient, gas diffusivity as well as wear resistance. It could be demonstrated that the new technical approach is suitable to parylene-coat the inner surfaces of tubes with high aspect ratios thereby achieving conformal coatings.

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

High-quality scaffolds play a vital role in tissue engineering. The frozen-form method (FFM) (also known as low-temperature deposition manufacturing) can be used to fabricate scaffolds from biomedical polymers. These scaffolds may have both macroporous and microporous characteristics and may incorporate bioactive compounds or biomolecules during the process. In addition, scaffolds produced at low temperatures can prevent the occurrence of thermal hydrolysis, thereby improving the mechanical properties of scaffolds. In fabricating high-quality (without deformation and collapse) bioscaffolds through the FFM, the most crucial requirement is the creation of a uniform low-temperature environment. This study developed a frozen-form additive manufacturing system that includes a uniform cryogenic device to generate the uniform distribution of a low-temperature environment over a local region to produce large scaffolds that will not deform and collapse. A large square scaffold block and a high aspect rati...

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.

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.

Biodegradable polyurethane elastomers (BioEPUR) are becoming increasingly important as biomaterials because they have excellent chemical, physico-mechanical and biological properties. This review presents the recent developments on BioEPUR and their potential applications in the biomedical and pharmaceutical fields. The aim of this work is to present an overview of the various methods of synthesis and properties of biomedical BioEPUR. Polyurethanes-based aliphatic or cycloaliphatic diisocyanates and polyesters, poly(ester-carbonate)s or copolymers of heterocyclic monomers were discussed.

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.

Surface engineering using plasma, grafting, and related techniques is an important area in biomaterials research and biomedical engineering. The burgeoning technology enables the modification of selected surface characteristics while the favorable bulk materials properties can be retained. In this invited mini-review, recent work related to surface modification of biomaterials by plasma-based and related techniques conducted in the Plasma Laboratory at City University of Hong Kong is described. Examples of new applications include enhancement of antimicrobial properties and cytocompatibility of plasma and surface-treated and nanostructured biomaterials, corrosion resistance of plasma-treated biodegradable metals, as well as targeted drug delivery capability and magnetic properties of surface-modified silica nanospheres and polymeric micelles.

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.

Nowadays, polymers are finding increasing use in a bewildering array of specialist applications. A good example of this is in the biomedical field. In this paper, some of the research work which is being carried out in Chiang Mai will be described. In its wider context, this paper also aims to show how the development of new polymers for such specialist applications depends on being able to control the polymers microstructure at each stage of its synthesis and processing.

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.

A novel organosilicon sulfobetaine was synthesized through the reaction of organosilicon containing tertiary amino with 1,3-propanesulfone. Then this organosilicon sulfobetaine was coated onto polyurethane and organosilicon surface to improve their blood compatibility. The existence of sulfobetaine structure on the surface of materials was revealed by ATR-FTIR and XPS. The thermo-capability of synthesized silicone rubber, containing sulfobetaine was revealed by TGA. The blood compatibilities of organosilicon sulfobetaine and other materials such as silicone and PU as reference coated with them were evaluated by platelet-rich plasma adhesion experiment. The novel segmented silicone rubber containing sulfobetaine structure showed perfect blood compatibility.

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).

Silk is a textile material, as well as one of the oldest biomaterials. However, the recent progress of biomedical science and technology has led to the replacement of silk by various biomaterials based on synthetic polymers. Despite the wide variety of biomaterials available, these materials suffer certain limitations that prevent them from meeting the various demands of the medical field. Therefore, silk continues to attract considerable interest as a promising biomaterial. This paper explains the fundamentals of silk protein, and reviews the many applications of silk biomedical polymers.

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.

The sol-gel derived bioactive glass short fibers in the system CaO-P2O5-SiO2 was prepared using air-spray method. SBF immersion test indicated that the fibers possessed satisfactory bioactivity. SEM, XRD, FTIR analysis revealed that the morphologies and bioactivity of the fibers could be significantly influenced by the composition and viscosity of the solution. The fibers are very promising biomaterials for applications to bone restoration and tissue engineering as the bone defects fillers or additives for strengthening of the biomedical polymers.

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.

A variety of bioactive composites have been investigated over the last two decades as substitute materials for diseased or damaged tissues in the human body. In this paper, the rationale and strategy of developing these composites are given. Major factors influencing the production and performance of bioactive composites are discussed. Some promising composites for tissue replacement and regeneration are reviewed. On the basis of past experience and newly gained knowledge, composite materials with tailored mechanical and biological performance can be manufactured and used to meet various clinical requirements.

The poly(α-ester)s are perhaps the most well known biomedical polymers and include polylactides, polyglycolides, poly(lactide-co-glycolides), polycaprolactones, and bacterial and other recombinant polyesters. Interestingly, these degradable polymers are tunable and have application beyond medicine. The polylactides and polyglycolides have the most extensive breadth of use, spanning research to the clinic, the polycaprolactones the next extensive, while the bacterial and recombinant polyesters are found in research and have not yet gained clinical traction. This chapter provides background regarding formulation and processing of these unique materials. A brief look is given to current and future biomedical applications.

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.

Biomaterials play a critical role in bone engineering, working as an artificial extracellular matrix to support regeneration. From the materials science point of view, natural bone is ceramic-polymer composite. It is not surprising that huge efforts have been invested into the development of bioceramics and composites that mimic that of native bone. This chapter provides a comprehensive review on the biomaterials used in bone tissue engineering, including bioceramics, polymers and composites. The rational of bone tissue engineering is briefly introduced first. This is followed by systematic review of bioceramic (e.g. calcium phosphates, hydroxyapatite and bioactive glasses), biomedical polymers (e.g. polylactic acid, polyglycolic acid and their copolymers) and polymer-based ceramic-filled composites. Each section includes discussions of the material’s biocompatibility and biodegradability and two essential features of biomaterials in most tissue engineering applications, followed by a detailed description of its mechanical properties. Finally, the major achievements and remaining challenges for biomaterials used in bone tissue engineering are summarised.

Therapeutic embolisation of blood vessels is a procedure commonly performed to treat a variety of conditions including bleeding problems, arterio-venous malformations (AVM), and benign and malignant hypervascular tumours. A range of degradable and permanent embolisation devices composed of natural and synthetic polymers may be used for such applications. Beads composed of a sulfonate-modified poly(vinyl alcohol) (PVA) hydrogel (DC Bead®) are finding wide-spread use for the occlusion and subsequent local, controlled and sustained delivery of chemotherapeutic agents directly within the vasculature of liver tumours. These so-called drug-eluting beads (DEB) are available in a series of calibrated size ranges for matching vessel size; have appropriate physico-mechanical properties to enable them to be delivered with ease through narrow gauge microcatheters; and have the ability to actively sequester and release positively charged anticancer drugs by an ion-exchange mechanism. This product has become one of the standards of care in the Western World for the treatment of intermediate primary liver cancer.

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.

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 .

The area of blood-lipid interaction with biomedical polymers has not been clearly defined. The purpose of the dissertation was to examine the interaction of the blood lipid, low density lipoprotein (LDL), with a select group of biomedical polymers. The adsorption characteristics of LDL was studied on filler-free poly(dimethyl siloxane) (PDMSO-FF), Biomer, Cardiomat 610, Kraton 1650, poly(hydroxy ethyl methacylate) (PHEMA) and glass as the control material. The low density lipoprotein was chosen because of its high cholesterol and cholesterol ester content which related to past in vitro studies showing steroidal lipid absorption, Low density lipoprotein was also chosen because of its pathophysiological role in atherogenesis. The data from this study suggest that LDL adsorption of polymer surfaces can occur by both electrostatic interactions and apolar or hydrophobic interactions. Adsorption of LDL to charged hydrophilic glass control surfaces occurred rapidly, reaching plateau concentrations within a minute. Adsorption of LDL to polymer surfaces appeared to be dependent upon the polymer hydrophobicity (or apolar nature) and to its flexibility (or dynamic nature) at the interface. Increased surface concentrations of LDL were observed for both hydrophobic and flexible polymer (Biomer versus PHEMA). Temperature was also found to enhance significantly the surface concentration of absorbed LDL at 37°C versus 25°C. This was suggested to be due to the core lipid phase transition at 36°C. Preliminary competitive absorption studies of LDL with albumin and serum suggest the LDL absorption occurs rapidly and preferentially. Preliminary studies on the role of LDL in calcification were not conclusive. The conclusion from this study suggested that LDL adsorption occurs as a function of polymer hydrophobicity, flexibility and temperature. Further studies are necessary to define the role of LDL in lipid absorption, materials compatibility in affecting the material integrity in an in vivo environment.