Polymeric biomaterials natural polymers

Lessons from nature have been incorporated into many research outcomes in the field of natural polymeric biomaterials. Natural polymers perform nicely as scaffold materials. Their chemical compositions and structural arrangements more closely resemble living tissue, and they have excellent biological properties. Nonetheless, because the natural polymers are derived from other living creatures, the pathogens and the potential immunological responses they stimulate may be concerns. Besides, it is very difficnlt to precisely control the fabrication of natural polymers. The limited number of sources is another challenge. 

Biomedical materials include metals, ceramics, natural polymers (biopolymers), and synthetic polymers of simple or complex chemical and/or physical structure. This volume addresses, to a large measure, fundamental research on phenomena related to the use of synthetic polymers as blood-compatible biomaterials. Relevant research stems from major efforts to investigate clotting phenomena related to the response of blood in contact with polymeric surfaces, and to develop systems with nonthrombogenic behavior in short- and long-term applications. These systems can be used as implants or replacements, and they include artificial hearts, lung oxygenators, hemodialysis systems, artificial blood vessels, artificial pancreas, catheters, etc. 

Along with a better understanding of biological processes involved in CNS disorders, many advances have been made in material science in combination with polymeric biomaterials for improving diagnostic modalities. Nano-sized carriers are made up of a variety of synthetic and natural polymers, which have been extensively studied for their multifunctionality and for their ability to extrava-sate to regions that are deep in the CNS. With the ability to... 

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). 

A main requirement for a polymeric candidate is its biocompatibility with biological tissues and fluids. Biocompatibility will depend on the polymer intrinsic chemical nature and the additives present. It is a complex issue not dealt with here. It is not always possible to distinguish the medical-grade polymers from the conventional polymers. They may come from a batch intended for general purposes, but are selected on the basis of clean condition or trace element analysis or mechanical properties. Subsequent processing requires clean room conditions and care to avoid any contamination. There is still some inherent uncertainty about constituents unless there has been complete disclosure and/or only a pure polymer is used. With new developments in polymeric biomaterials, the situation should improve. 

The objective of this chapter is to review degradable materials, including polymers, and the resulting delivery systems fabricated from them that are usefid for the delivery of proteins and peptides. Owing to the diverse nature of the subject area, we have chosen to divide the chapter into sections on hydrophobic synthetic polymers, hydrophilic polymeric biomaterials, and hydrophobic nonpolymeric biomaterials. Each section seeks to briefly highlight ftie chemist and characteristics of the polymer or matrix and provide recent examples of their use in the delivery of proteins. 

Both synthetic polymers and natural polymers have been broadly studied as biodegradable polymeric biomaterials. Polymeric biomaterials based biodegradation entails cleavage of hydrolytically or enzymatically sensitive bonds in the polymer resulting in to polymer erosion [8]. Based on the means of degradation, polymeric biomaterials can be further divided into ... 

Science and technology of polymeric biomaterials as a whole have seen extraordinary development, research interest and investment by industry in recent decades. Within this broad field, natural polymers have in particular witnessed major studies. Indeed biopolymers have virtually moulded the modem world and transformed the quality of life in iimumerable areas of human activity. They have added new dimensions to standards of life and inexpensive product development. From transportation to communications, entertaimnent to health care, the world of biopolymers has touched them all. 

This chapter provides a brief overview of some of the recent developments in the field of polymeric biomaterials with a particular emphasis on the articles included in this book (2-22). The research being done in this field is diverse and takes on several directions due to its multi disciplinary nature. It helps to organize these developments broadly into three sections (a) Synthetic approaches to polymer based biomaterials (b) characterization related development and (c) polymeric surfaces and (d) other biomedical applications of polymers. 

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