Synthesis of poly(lactide-ran-MOHEL) and its biodegradation with proteinase K

Homopoly(L-lactide) and homopoly(D,L-lactide) were almost inert for biodegr adation with tricine buffer or normal enzymes such as bromelain, pronase, a nd cholesterol esterase but biodegradable with proteinase K. Significantly enhanced biodegradation was observed when an optically active (R)- or (S)-3 -methyl-4-oxa-6-hexanolide (MOHEL) unit was introduced into poly(L-lactide) [poly(L-LA)] or poly(D,L-lactide) [poly(D,L-LA)] sequences. Poly[L-LA-ran- (R)-MOHEL] in molar ratios of 86/14 to 43/57 showed good biodegradability t hat was independent of crystallinity. The biodegradation of polymers with p roteinase K increased in the following order: poly[D,L-LA-ran-(R)-MOHEL] > poly[L-LA-ran-(R)-MOHEL] > poly[D,L-LA-ran-(S)-MOHEL] > poly[L-LA-ran-(S)-M OHEL] > poly(R)-MOHEL > poly(D,L-LA) The number-average molecular weight, m olecular weight distribution, glass-transition temperature, and melting tem perature did not change before and after the biodegradation of poly[L-LA-ra n-(R)-MOHEL], indicating that the degradation occurred from the polymer sur face. (C) 2001 John Wiley & Sons, Inc.