Synthesis of a carbon dioxide-based amphiphilic block copolymer and its evaluation as a nanodrug carrier

A series of novel amphiphilic block copolymers poly(propylene carbonate)-block-mono-methoxy poly(ethylene oxide) (PPC-b-MPEG) composed of hydrophobic PPC segments and various lengths of hydrophilic MPEG segments was synthesized via "Click Chemistry" between azido-terminated PPC and alkynyl-terminated MPEG. The structure of the copolymers was characterized by FTIR, H-1 NMR and C-13 NHR techniques. Chlorpyrifos (CHP) was encapsulated within micelles through diffusion dialysis method, leading to the formation of CHP-loaded PPC-b-MPEG micelles. The resulting micelles were characterized further by dynamic light scattering (DLS) and scanning electron microscope. The results indicated that PPC-b-MPEG could self-assemble into nanosized micelles with PPC cores and PEG shells in aqueous solution. And the size, zeta potential, morphology, critical micelle concentration of PPC-b-MPEG micelles can be altered by changing the lengths of the PEG segments. CHP was encapsulated into PPC-b-MPEG(2k) micelles with loading capacity of 9.02% and entrapment efficiency of 77.28%. These results suggested that PPC-b-MPEG micelles would be a potential carrier for controlled release.