Controlled release of bovine serum albumin using MPEG-PCL diblock copolymers as implantable protein carriers

MPEG-PCL diblock copolymers consisting of methoxy polyethylene glycol (MPEG) and poly(ε-caprolactone) (PCL) as drug carriers were synthesized by ringopening polymerization. It is possible to control the balance between hydrophilic and hydrophobic by changing the MPEG and the ratio of ε-CL to MPEG. Implantable wafers were easily fabricated by the direct compression method after physical mixing of diblock copolymers and bovine serum albumin-fluorescein isothiocyanate (BSA-FITC) as a model protein drug. The BSA release from wafers prepared by MPEG-PCL diblock copolymers were higher than that from PCL with the physical blending of MPEG. The wafers prepared by a variety of MPEG-PCL diblock copolymers exhibited the controlled BSA release profiles with a dependence on MPEG-PCL diblock copolymer compositions. In addition, the changing of MPEG and PCL molecular weights within MPEG-PCL diblock copolymer controlled the initial burst of BSA. We confirmed that the diblock copolymers could be served as protein delivery carrier in implantable wafer form.