Comparison of two pegylated copolymeric micelles and their potential as drug carriers.

The aim of this study was to evaluate the ability of forming micelles from two types of synthesized diblock pegylated amphiphilic copolymers and their potential as a drug carrier. Two lactone monomers, epsilon-caprolactone (CL) and delta-valerolactone (VL), were copolymerized with methoxy poly(ethylene glycol) (MePEG), respectively. The properties of copolymers were investigated and their biocompatibility was tested through an in vitro cytotoxicity study. The influences of the type of lactone monomer (CL and VL) and the feed molar ratios of lactone/MePEG (50/1, 80/1, 160/1) on the performance and release behavior of drug-loaded micelles were investigated. The opening of CL and VL rings by MePEG was efficient, and the pegylation of poly(lactone)s allowed copolymers possessing amphiphilic property and efficiently self-assembled to form micelles with a low critical micelle concentration (CMC) in the range of 10(-7)-10(-8) M. The nano-sized micelles were able to incorporate hydrophobic drug and regulate drug release, and the release of drug was dominated by the hydrophobic poly(lactone) chain length. Although both amphiphilic copolymers exhibited similar controlled release character, the PCL/MePEG micelles possessed lower CMC, higher biocompatibility, and higher drug loading than PVL/MePEG micelles. These suggested that results choosing pegylated PCL as a drug carrier could be better than PVL/MePEG.