Preparation and characterization of thermo-sensitive micelles composed of PSt-b-P(DEA-co-DMA)

Abstract

AbstractThe amphiphilic block copolymer polystyrene-b-poly(N,Ndiethylacrylamide- co-N,N-dimethylacrylamide) (PSt-b-P(DEA-co-DMA)) was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization of DEA and DMA using PSt as macro chain transfer agent (PSt CTA) and N,N-azobisisobutyronitrile (AIBN) as initiator. Polymeric micelles were prepared by dialysis of the block copolymer solution in tetrahydrofuran (THF) against aqueous media. The polymeric micelles PM73 based on block copolymer P73, which was prepared with molar ratio DEA/DMA/PSt CTA/AIBN = 700:300:10:1, exhibited a lower critical solution temperature (39.2°C) in aqueous solution which was a little higher than the human body temperature. Polymeric micelles PM73 showed a unimodal size distribution with an average diameter of 24.2±0.5 nm. The micelles were thermodynamically stable in aqueous media above the critical micelle concentration (1 mg/l). The anti-inflammation drug, prednisone acetate, was incorporated into PM73 as the model drug. The loading capacity was found to be around 8 wt%, and the drug-loaded micelles showed similar size distribution patterns (monodisperse with an average diameter of 32.1±0.5 nm) and morphology (spherical) to the empty micelles. The drug-loaded micelles showed remarkable thermoresponsive drug release behavior, in response to the micellar structural change.