Mixed micelles from methoxy poly(ethylene glycol)-polylactide and methoxy poly(ethylene glycol)-poly(sebacic anhydride) copolymers as drug carriers

mPEG-PLLA (poly l-lactic acid) is synthesized by ring-opening polymerization of lactide and conjugation with mPEG. Sebacic acid is modified with acetic anhydride and condensed with mPEG to form mPEG-PSA (poly sebacic anhydride). The micelles formed by mPEG-PLLA are characterized by slow degradation and low drug encapsulation efficiency; on the contrary, mPEG-PSA micelles are characterized by rapid degradation but high encapsulation efficiency. They can merge into spherical micelles (Φ = 140 nm) by self-assembly in water. The mixed micelles can successfully encapsulate a typical hydrophobic drug (curcumin), and significantly improve its solubility. Experimental results show that the mixed micelles have the features of high encapsulation efficiency and slow degradation.