Preparation and release behavior of methoxy poly(ethylene glycol)-poly(L-lactide-co-glycolide) wafer containing albumin

A series of methoxy poly(ethylene glycol) (MPEG)-poly(L-lactide-co- glycolide) (PLGA) diblock copolymers were synthesized by ring-opening polymerization of L-lactide and glycolide with carbitol (134 g/mole) or different molecular weights of MPEG (550, 2000, and 5000 g/mole) as an initiator in presence of Sn(Oct)₂. The properties of diblock copolymers were characterized by using ¹H-NMR, GPC, and XRD. After uniform mixing of block copolymers and 1% albumin bovine-fluorescein isothiocyanate (FITC-BSA) with a freeze miller, the wafers loaded FITC-BSA were fabricated by using a mold with a dimensions of 3 mm X 1 mm diameter. The release profiles of FITC-BSA and the pH changes of wafer were examined using pH 7.4 PBS for 30 days at 37°C. The release profiles of albumin showed fast initial burst as the molecular weights of MPEG increased. As a result of this study, the release behavior of BSA was controlled with introducing MPEG in the block copolymers.