THE BIODEGRADATION OF POLY(ESTER-ETHER-ESTER) BLOCK-COPOLYMERS IN A CELLULAR ENVIRONMENT IN-VITRO

In this paper we report about the biodegradation of tri-block poly(est er-ether-ester) copolymers obtained by reaction of preformed poly(ethy lene glycol) (PEG) with two different lactone monomers, i.e. epsilon-c aprolactone (CL) and L-lactide (LA). The two series of copolymers will be indicated as PCL-POE-PCL and PLA-POE-PLA. We identified and measur ed by HPLC analysis the amount of degradation products of the poly(est er-ether-ester) copolymers; three copolymers were tested for each seri es during 3-8 week experiments. The experiments were carried out both in the presence and absence of fibroblast cell populations. We evaluat ed at the same time the decrease of copolymer molecular mass after deg radation by means of intrinsic viscosity [eta] measurements. From the [eta] measurements we can conclude that the higher the hydrophilicity of the material, the faster the rate of decrease of its intrinsic visc osity with time. The HPLC results indicate that the amount of the degr adation products, i.e., respectively, the monomers 6-hydroxyhexanoic a cid and L-lactic acid, is a function of both hydrophilicity of the mol ecule and the lateral block length. When the fibroblast cell populatio ns were present in the same wells together with the biodegradable copo lymers, signs of cellular metabolism of the degraded monomers were det ected.