Polymers of malic acid and 3-alkylmalic acid as synthetic PHAs in the design of biocompatible hydrolyzable devices

Poly(beta-malic acid) and poly(beta-3-alkylmalic acid) derivatives, as synt hetic polyhydroxyalkanoates (PHAs), present several advantages as macromole cular materials for temporary biomedical applications. Indeed, such polymer s, which can be synthesized through different chemical and biological route s, have cleavable ester beads in their backbone for hydrolytic degradation, stereogenic centres in the monomers units for controlling the macromolecul ar structure, bioassimilable or non-toxic repeating units and lateral chemi cal functions which can be adapted to specific requirements. The strategy f or building such complex architectures, with one or several specific pendan t groups, is based on the anionic ring-opening polymerization or copolymeri zation of the large family of malolactonic and 3-alkylmalolactonic acid est ers. Because we are able to control the monomer synthesis and the polymeriz ation step, we have been able to prepare different degradable materials for the biomedical field; such as: degradable associating networks made up by the association of random copolyesters containing a small percentage of hyd rophobic moieties and beta-cyclodextrin copolymers; degradable macromolecul ar micelles constituted by degradable amphiphilic block copolymers of poly( beta-malic acid) as hydrophilic segments and poly(beta-alkylmalic acid alky l esters) as hydrophobic blocks; and degradable nanoparticles made up by hy drophobic poly(beta-malic acid alkyl esters) derivatives. We have also prep ared a terpolymer which exhibits growth factor-like properties in vivo. Fin ally, poly-(beta-malic acid) has been used as an additive in the preparatio n of peritoneal dialysis bags. (C) 1999 Elsevier Science B.V. All rights re served.