BIORESORBABILITY AND BIOCOMPATIBILITY OF ALIPHATIC POLYESTERS

The field of biodegradable polymers is a fast growing area of polymer science because of the interest of such compounds for temporary surgical and pharmacological applications. Aliphatic polyesters constitute the most attractive family among which poly(alpha-hydroxy acids) have been extensively studied. In the past two decades, several excellent reviews have been published to present the general properties of aliphatic polyesters. The aim of this, paper is to complete the information collected so far with a special attention to the complex phenomena of biodegradability and biocompatibility. Indeed, the degradation of a polymer leads to the delivery of low molecular weight degradation by-products whose effects on the host body have to be considered. The consequences of the absence of standard terminology are first discussed with respect to words such as biodegradable and bioresorbable. Poly(alpha-hydroxy acids) derived from lactic and glycolic acids are then introduced in order to make easier the critical discussions of the following problems from literature data: biocompatibility, biodegradability, bioresorbability, mechanism of hydrolysis (enzymatic vs simple chemistry), polymodality of molecular weight distributions during degradation and the effects of the presence of oligomers. Finally, some specific comments are made on other aliphatic polyesters such as poly(hydroxy butyrate) and poly(beta-malic acid).