Study on core-stabilized polymeric micelle as a potential drug carrier

Abstract

Amphiphilic diblock copolymers composed of poly(ethylene glycol)-b-poly(ß-benzyl L-aspartate) (PEG-b-PBLA) as a hydrophilic and hydrophobic block were synthesized and their amino terminal group were modified with methacryloyl group. Subsequently, their nanoscale self-assembly structure, polymeric micelle was stabilized through core-polymerization using UV photopolymerization method. BLA-NCA, as a monomer of PBLA block, was synthesized by phosgenation of ß-benzyl L-aspartate using triphosgen and PEG-b-PBLA amphiphilic block copolymer was obtained through copolymerization of BLA-NCA by ring opening polymerization using PEG as a primary amine macroinitiator. Methacryloyl-modified poly(ethylene glycol)-b-poly(ß-benzyl L-aspartate)-methacryloyl (PEG-b-PBLA-MA) was synthesized through acylation reaction of amine terminal of PBLA block. The synthesis was verified by 1H-NMR, FT-IR, analysis. To study solution properties of water soluble copolymers only four copolymers with less than 20 degree of polymerization (DP) were employed. Nanoscopic self-assembled structure, polymeric micelle was prepared by sonication using a bath-type sonifier. The self-assembling behavior in aqueous medium was studied using dynamic light scattering and fluorescence spectroscopy. Then, PEG-b-PBLA-MA was loaded with DMPA (2,2-dimethoxy-2-phenylacetophenone), photoinitiator, by O/W emulsion or dialysis method according to DPs and followed by photopolymerization with 365nm-UV mercury lamp. Only polymeric micelle from PEG-b-PBLA-MA with DP 6 was successfully photopolymerized, of which molecular weight was determined by gel permeation chromatography(GPC). In order to study enhanced micellar stability dilution with water and treatment with non-selective, organic solvent were done and their morphology was identified with AFM images.