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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...

Enzyme immobilization has been accepted as a powerful technique to solve the drawbacks of free enzymes such as limited activity, stability and recyclability under harsh conditions. Different from the conventional immobilization methods, enzyme immobilization in inorganic hybrid nanoflowers was executed in a biomimetic mineralization manner with the advantages of mild reaction conditions, and thus it was beneficial to obtain ideal biocatalysts with superior characteristics. The key factors influencing the formation of enzyme-based inorganic hybrid nanoflowers were elucidated to obtain a deeper insight into the mechanism for achieving unique morphology and improved properties of immobilized enzymes. To date, immobilized enzymes in inorganic hybrid nanoflowers have been successfully applied in biocatalysis for preparing medical intermediates, biodiesel and biomedical polymers, and solving the environmental or food industrial issues such as the degradation of toxic dyes, pollutants and allergenic proteins. Moreover, they could be used in the development of various biosensors, which provide a promising platform to detect toxic substances in the environment or biomarkers associated with various diseases. We hope that this review will promote the fundamental research and wide applications of immobilized enzymes in inorganic hybrid nanoflowers for expanding biocatalysis and biosensing.

Polypeptides are one kind of promising biodegradable and biocompatible biomedical polymers with the structural units of various α-amino acids. Polypeptides were first polymerized by the ring-opening polymerization (ROP) of α-amino acid N-carboxyanhydrides (NCAs) by Leuchs and Hermann in 1906. In the past decades, several effective strategies, including the selection of initiators, the adjustment of reaction conditions, and the introduction of catalysts, have been reported to improve the controllability of the ROP of various α-amino acid NCAs to synthesize different polypeptides with precise chemical structures and low polydispersity indexes. In this Review, the strategies, mechanisms, challenges, and opportunities for controlled synthesis of polypeptides by the ROP of different α-amino acid NCAs have been declared.

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.

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.

[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.

Biodegradable polyesters gain significant attention because of their wide potential biomedical applications. The ring-opening polymerization method is widely used to obtain such polymers, due to high yields and advantageous properties of the obtained material. The preparation of new, effective, and bio-safe catalytic systems for the synthesis of biomedical polymers is one of the main directions of the research in modern medical chemistry. The new diethylzinc/propyl gallate catalytic system was first used in the copolymerization of &epsilon, caprolactone and rac-lactide. In this paper, the activity of the new zinc-based catalytic system in the copolymerization of cyclic esters depending on the reaction conditions was described. The microstructure analysis of the obtained copolyesters and their toxicity studies were performed. Resulted copolyesters were characterized by low toxicity, moderate dispersity (1.19&ndash, 1.71), varying randomness degree (0.18&ndash, 0.83), and average molar mass (5300&ndash, 9800 Da).

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.

Management of fungal biofilms represents a significant challenge to healthcare. As a preventive approach, minimizing adhesion between indwelling medical devices and microorganisms would be an important step forward. This study investigated the anti-fouling capacity of engineered nanoscale topographies to the pathogenic yeast Candida albicans. Highly ordered arrays of nano-pit topographies were shown to significantly reduce the physical adherence capacity of C. albicans. This study shows a potential of nanoscale patterns to inhibit and prevent pathogenic biofilm formation on biomedical substrates.

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...

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.

In the past few years, research and the development of biomedical polymers and processing technologies for biomedical applications have received growing attention. Among the most attractive technologies, additive manufacturing (commonly known as three-dimensional printing) is highly suitable for producing sophisticated and tailor-made scaffolds for biomedical applications due its inherent advantages of customizability and the ability to create complex shapes with precision. Moreover, this is a time-saving approach, being far more reproducible than conventional techniques to obtain scaffolds. Additive manufacturing (AM) includes a wide variety of manufacturing techniques and it is being used in personalized prosthetic/implant devices for otorhinolaryngology, dentistry, orthopedics, and craniofacial reconstruction, among others. Tissue engineering and controlled drug-release systems are also important research fields which use AM as a tool for designing accurate, structured, and tailored functional structures. However, there are some limitations for processing new materials using AM techniques. Furthermore, there is an increasing need for new biocompatible and/or bioresorbable materials with different mechanical properties, degradation rates, and surface requirements to be processed for a broad range of applications. In the past years, biocompatible and biodegradable segmented polyurethanes (SPUs) have been investigated for their applications in tissue engineering, controlled drug-release systems, wound dressings, and many biomedical devices. SPU and their composites with poly(ethylene glycol), cellulose, starch, gelatin, alginate, fibrinogen, and collagen, among others, have been explored through different AM techniques for biomedical applications. This chapter aims to review the use of novel AM as microfabrication tools for bioresorbable SPU elastomers and SPU composites. Current advances in 3D printing of SPU are described and commented on. Advantages and shortcomings of the current approaches, as well as future perspectives are outlined. Finally, a vision for future research on this topic is presented.

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.

The past decade has seen growing interest in the investigation of peptides with antimicrobial activity (AMPs). One approach utilized in infection control is incorporation of antimicrobial agents conjugated with the polymers. This review presents the recent developments on polymeric AMP carriers and their potential applications in the biomedical and pharmaceutical fields.

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.

As discussed in Chap. 1, polymeric biomaterials of both natural and synthetic origin constitute an important class of biomedical materials that are used extensively in various applications ranging from drug delivery to tissue engineering. The use of natural polymers such as cellulose and collagen for various medical applications dates back to centuries.

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.

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).