Biodegradable polymers development

However, attitudes are slowly changing. During the last few years there have been a number of positive trends that are encouraging biodegradable polymer development. These include ... 

Table 13.14 Main impact categories and subcategories in LCA studies for biodegradable polymers (developed on the basis of Udo de Haes [47])...

Certain bacterial species produce polymers of y-hydroxybutyric acid and other hydroxyalkanoic acids as storage polymers. These are biodegradable polymers with some desirable properties for manufacture of biodegradable packaging materials, and considerable effort is being devoted by ICI Ltd. and others to the development of bacterial fermentation processes to produce these polymers at a high molecular weight (66). 

A novel polymerized vesicular system for controlled release, which contains a cyclic a-alkoxyacrylate as the polymerizable group on the amphiphilic structure, has been developed. These lipids can be easily polymerized through a free radical process. It has been shown that polymerization improves the stabilities of the synthetic vesicles. In the aqueous system the cyclic acrylate group, which connects the polymerized chain and the amphiphilic structure, can be slowly hydrolyzed to separate the polymer chain and the vesicular system and generate a water-soluble biodegradable polymer. Furthermore, in order to retain the fluidity and to prepare the polymerized vesicles directly from prev lymerized lipids, a hydrophilic spacer has been introduced. 

In the last few years there have been new creative methods of preparation of novel hydrophilic polymers and hydrogels that may represent the future in drug delivery applications. The focus in these studies has been the development of polymeric structures with precise molecular architectures. Stupp et al. (1997) synthesized self-assembled triblock copolymer, nanostructures that may have very promising applications in controlled drug delivery. Novel biodegradable polymers, such as polyrotaxanes, have been developed that have particularly exciting molecular assemblies for drug delivery (Ooya and Yui, 1997). 

A method was recently developed to deliver plasmid DNA locally to cells involved in wound repair (Bonadio et al., 1999 Fang et al., 1996 Shea et al., 1999). The technique involves the introduction of a porous, biodegradable polymer matrix into the wound site (Bonadio et al., 1998). The scaffold (a gene activated matrix, or GAM), in its simplest form comprises plasmid DNA and the polymer matrix (Bonadio, 2000). Naked... 

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