Biocompatible polymers, molecular design

The molecular design of biocompatible polymers is classified into four categories... 

Chitin is a (l->4)-linked 2-acetoamido-2-deoxy-g-D-glucan, and chitosan is its N-deacetylated product. These polysaccharides are naturally abundant and are present in the cuticles of insects and in the cell walls of plant pathogens, absent in the higher plant kingdom. Chitin and chitosan are (a) natural, (b) biocompatible, (c) almost nontoxic, (d) biodegradable, and (e) bioactive polymers. Our interest in these polymers is two-fold. (1) the molecular design of chitin and chitosan by chemical modification (Figure 1) in view of (a) the inversion of their molecular conformation, 3 (b) the development of their potential molecular... 

One of the requirements very often placed on polymers designed for the use in an organism (and, at the same time, a very vaguely defined requirement) is their biocompatibility . Biocompatibility should not be understood as an inherent property of a certain polymer but rather as a result of a dynamic process including the rate of polymer accumulation and duration of its persistence in a given compartment, its modification, and the rate of its clearance from the cells and ultimately from the body. All these variables are controlled not only by the molecular parameters of a particular polymer but also by the dose, route and frequency of its administration, which, on the other hand, are conditions dictated by the purpose of its application. 

Biomaterials. Adsorbed polymers find many apphcations as surface modifiers in biomedical apphcations. By choosing a combination of hydrophobic and hydrophilic copolsrmers, surfaces can be modified to make them biocompatible (65) (see Biomolecules at Interfaces). In the area of tissue engineering (qv), adsorbed layers with specihc amino acid sequences can be used to promote cell adhesion and proliferation. The recent developments in the design of biochips to analyze specihc DNA molecules also take advantage of this technology. Polymer adsorption on patterned surfaces can be used to mimic pattern recognition. This effect can be used to develop sensors and molecular-scale separation processes (66). 

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