Biomaterials for medical applications

After almost half a century of use in the health field, PU remains one of the most popular biomaterials for medical applications. Their segmented block copolymeric character endows them with a wide range of versatility in tailoring their physical properties, biodegradation character, and blood compatibility. The physical properties of urethanes can be varied from soft thermoplastic elastomers to hard, brittle, and highly cross-linked thermoset material. 

The wealth of natural examples provides immense inspiration for the molecular design of novel peptide-based materials that can be potentially applied as devices, sensors, and biomaterials for medical applications. In addition to hierarchical self-assembly, nature uses other mechanisms, for example, enzyme-mediated covalent cross-linking, to build up structural proteins and higher-ordered structures. In the following sections we will focus on manmade peptide-based materials that belong to the three classes listed below. They will be split with respect to the underlying design concept into materials formed by ... 

The opportunity for using protein-based polymers as biomaterials for medical applications comes with demonstration of the biocompatibility of the basic hydrogel and elastic and plastic states of the protein-based polymers, and it comes with the capacity to produce protein-based polymers by microbial fermentation with sufficiently low-cost production for a broad range of medical applications. 

Degradable pol mieric biomaterials for medical applications are particularly preferred for (1) ... 

The rate of degradation depends on a variety of parameters including the LA/GA ratio, molecular weight, and the shape and structure of the matrix. There has been extensive investigation into their use as biomaterials for medical applications, thanks to their unique properties, such as controllable degradation and good processability (Miller et al., 1977 Tiainen et al., 2002). 

Fiordeliso, J., Bron, S. and Kohn, J. (1994) Design,. synthesis, and preliminary characterization of tyrosine-containing polvarylates New biomaterials for medical applications. /. Biomater. Sci. (Polym. 

Materials intended for use inside the body have to be approved by regulatory agencies. The minimal requirements of biomaterials for medical applications include nontoxicity, effectiveness, and sterilizability (Table 27.1). Although many currently available biomaterials meet these requirements, most of them lack biocompatibility. 

Even though great advances have been made in the field of biomaterials for medical applications, as was mentioned before, the development of a polymeric matrix capable of acting as drug reservoir, which is also capable of having full control of the release rate of drugs, is still in its infancy. Biomaterials capable of replacing human tissue... 

The toxicity of LCER nanocomposite is lower than that of nanocomposite contains no LCER and commercial dental restorative materials by both MTT and LDH tests (Fig. 19.8). Therefore, the LCER nanocomposite is a good biomaterial for medical applications. 

Ikada Y. Surface modification of polymers for medical application. Biomaterials, 1994, 15, 725-736. James SJ, Pogribna M, Miller BJ, Bolon B, and Muskhelishvili L. Characterization of cellular response to silicone implants in rats Implications for foreign-body carcinogenesis. Biomaterials, 1997, 18, 667-675. 

In dentistry, silicones are primarily used as dental-impression materials where chemical- and bioinertness are critical, and, thus, thoroughly evaluated.546 The development of a method for the detection of antibodies to silicones has been reviewed,547 as the search for novel silicone biomaterials continues. Thus, aromatic polyamide-silicone resins have been reviewed as a new class of biomaterials.548 In a short review, the comparison of silicones with their major competitor in biomaterials, polyurethanes, has been conducted.549 But silicones are also used in the modification of polyurethanes and other polymers via co-polymerization, formation of IPNs, blending, or functionalization by grafting, affecting both bulk and surface characteristics of the materials, as discussed in the recent reviews.550-552 A number of papers deal specifically with surface modification of silicones for medical applications, as described in a recent reference.555 The role of silicones in biodegradable polyurethane co-polymers,554 and in other hydrolytically degradable co-polymers,555 was recently studied. 

In addition to dense monolithic ceramics, porous silicon nitrides are gaining more importance in technological applications [24], Some porous silicon nitrides with high specific surface area have already been applied as catalysis supports, hot gas filters and biomaterials [25], There is an emerging tendency to facilitate silicon nitride as biomaterial, because of specific mechanical properties that are important for medical applications [25], Moreover, in a recent study it was shown that silicon nitride is a non-toxic, biocompatible ceramic which has the ability to propagate human bone cells in vitro [25], Bioglass and silicon nitride composites have already been realized to combine... 

In contrast, in experimental and clinical medicine only a few groups have been active in the research and development of shaped BC as implant biomaterial [65-76]. Therefore - from our viewpoint - it is necessary to specify BC design and handling for medical applications in detail. 

Recently, considerable attention has been directed on biomaterials that are used in contact with living tissue and biological fluids for medical applications. One of the... 

Ikada, Y. 1994. Surface modification of polymers for medical applications. Biomaterials, 15 725-36. 

The term biomaterials encompasses all materials used for medical applications that are interfaced with living systems. Although this definition addresses specifically materials used in contact with living systems (intra-corporeal uses), other systems developed for extracorporeal uses 1-4) are also commonly classified as biomaterials. 

FIGURE 5.82 Microcapsule formation by interfacial and in situ polymerization. A and B are reactants, while— (A-B) —and—(A) —are polymeric products. See text for explanation. (After Thies, C. 1989. Biomaterials and Medical Applications, Encyclopedia Reprint Series, J. I. Kroschwitz, ed., pp. 346-367. John Wiley, New York.)... 

Singh et al., in Chapter 13, Nanobiomaterials applications in biomedicine and biotechnology, review the fabrication of nanoscale biomaterials for medical and biotechnological applications. Nanoscale molecular tools in nanobiomedicine are used for diagnostic purposes and improvement of human health. Pivotal studies, both nonclinical and clinical, in the aspects of safety and tolerance are the necessity of recent times in order to formulate their potential commercial application. 

For medical applications, in our view, mechanical resonances (see Section 9.4.2.3) present barriers to antibody interaction such that these soft elastic biomaterials exhibit a remarkable biocompatibility otherwise considered impossible for foreign proteins. As a specific example for medical and nonmedical applications, the author believes that the finding of mechanical resonances, so innovative as to be denounced as artifact by those constrained by the idols of the present, constitutes opportunities for the future ranging from biosensors capable of single molecule detection to hearing protection and underwater sound absorption. 

Biomaterials have been defined as materials which are compatible with living systems. In order to be biocompatible with host tissues, the surface of an implant must posses suitable chemical, physical (surface morphology) and biological properties. Over the last 30 years, various biomaterials and their applications, as well as the applications of biopolymers and their biocomposites for medical applications have been reported. These materials can be classified into natural and synthetic biopolymers. Synthetic biopolymers are cheaper and possess better mechanical properties. However, because of the low biocompatibility of synthetic biopolymers compared with that of natural biopolymers, such as polysaccharides, lipids, and proteins, attention has turned towards natural biopolymers. On the other hand, natural biopolymers usually have weak mechanical properties, and therefore much effort has been made to improve them by blending with some filler. 

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