Biomedical composites physical properties

The above analysis takes the synthesis methods, the performance affected by the dispersion of CNTs, enhanced physical properties and the latest applications of carbon nanotube/polyurethane composites described in literature reports as the reference point. In the interest of brevity, this is not a comprehensive review, however, it goes through numerous research reports and applications which have been learned and described in the recent years. Despite that, there are still many opportunities to synthesize new carbon nano-tube/polyurethane systems and to modify carbon nanotubes with new functional groups. The possibility of producing modern biomedical and shape memory materials in that way makes the challenge of the near future. 

A wide variety of natural and synthetic materials have been used for biomedical applications. These include polymers, ceramics, metals, carbons, natural tissues, and composite materials (1). Of these materials, polymers remain the most widely used biomaterials. Polymeric materials have several advantages which make them very attractive as biomaterials (2). They include their versatility, physical properties, ability to be fabricated into various shapes and structures, and ease in surface modification. The long-term use of polymeric biomaterials in blood is limited by surface-induced thrombosis and biomaterial-associated infections (3,4). Thrombus formation on biomaterial surface is initiated by plasma protein adsorption followed by adhesion and activation of platelets (5,6). Biomaterial-associated infections occur as a result of the adhesion of bacteria onto the surface (7). The biomaterial surface provides a site for bacterial attachment and proliferation. Adherent bacteria are covered by a biofilm which supports bacterial growth while protecting them from antibodies, phagocytes, and antibiotics (8). Infections of vascular grafts, for instance, are usually associated with Pseudomonas aeruginosa Escherichia coli. Staphylococcus aureus, and Staphyloccocus epidermidis (9). 

In addition to polyesters, other types of biodegradable polymers such as polyurethanes, polyanhydrides, poly(amino acids), poly(vinyl alcohol), and poly(ester amide), are generally processable by conventional processing techniques for plastics. Their physical properties can be expected to be comparable, and sometimes can be used to supplement biodegradable polyesters. Although these polymers are more likely used in niche applications or incorporated with other polymers by making composite materials, they obviously provide more material choices in the design and manufacture of various biomedical products. 

Zhao, H.G., Ma, L., Gao, C.Y., Shen, J.C., 2009. A composite scaffold of PLGA microspheres/ Hbrin gel for cartilage tissue engineering fabrication, physical properties, and cell responsiveness. Journal of Biomedical Materials Research B 88B (1), 240—249. 

The results reported in this work showed that mechanical and transport properties of Poly-2-hydroxyethylmethacrylate are strongly affected by the composition of the reaction mixture, and in particular by the ratio water/diacetine. It has been shown that it is possible, using different types and amounts of additives, to obtain a wide range of physical properties of swollen PHEMA as required for various biomedical applications. Moreover, the spongy samples could be of interest in the design of biomedical implants whose morphology is characterized by porous structure with very high water contents. 

Plasma polymerization is a strongly system-dependent process, which is not determined only by the monomer used but by plasma parameters. The structure and composition, physical and chemical properties of a plasma polymer and its deposition rate depend on many parameters for a given monomer or gas mixture type of reactor, frequency of discharge (RF, MW), excitation voltage, power delivered, flow rate of monomer, working gas pressure, substrate temperature, substrate size and its position, etc. Detailed discussion of plasma polymerization processes can be found in several reviews and books." Only the basic phenomena of plasma polymerization and plasma polymers for biomedical applications are described in this section. 

Ion beam-based treatments typically involve addition (the implanted ions), removal (sputtering) and in some cases change (formation of new compounds) of the target material at its outermost surface. As a consequence, ion implantation treatments induce a change in the structure and nanotopograpy of the treated surface, in the physical properties, chemical composition, and overall in its biological properties. " Ion implantation is used in semiconductor device fabrication, metal finishing, and materials science research as well as the biomedical applications presented later. 

For the development of new materials with potential biomedical application, it is crucial to understand their overall in vivo properties. Parameters such as morphology, size, composition, surface chemistry, and associated physical properties of VNPs can greatly influence their toxicological nature, as well as accumulation and systemic clearance (Powers et al., 2006). Thus, a complete understanding of the pharmacokinetics, blood half-life, stability, biodistribution, and immunogenicity is crucial to assess the viability of virus-based nanoparticles. 

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