Temperature-responsive diblock copolymers bearing biocompatible pendant phosphorylcholine groups

Abstract

Water-soluble polymer micelles which can incorporate guest molecules and release them in response to external stimuli can be used as drug delivery systems (DDS). In this study, temperature-responsive diblock copolymers composed of a block that contains pendant phosphorylcholine groups (PMPC) and a thermo-responsive poly(N,N-diethylacrylamide) (PDEA) block were prepared via controlled radical polymerization. PMPC dissolves in water independent of temperature and thus it is difficult for the immune system to recognize it as a foreign substance. Above the critical aggregation temperature (CAT), the diblock copolymers form polymer micelles composed of a hydrophobic PDEA core and a hydrophilic and biocompatible PMPC shell. Below the CAT, the polymer micelles dissociate, because the PDEA block becomes hydrophilic. Above the CAT the polymer micelles can incorporate hydrophobic guest molecules into the PDEA core. On the other hand, below the CAT these guest molecules are released into the bulk water phase from the micelles.