Folate-conjugated methoxy poly (ethylene glycol)/poly (L-Alanine) amphiphilic block copolymeric micelles for targeted delivery of paclitaxel

Folate has been used as a targeting moiety of various anticancer agents to increase their cellular uptake within target cells since folate receptors(FR) are vastly overexpressed in many tumors. In this study, amphiphilic block copolymers composed of methoxy poly (ethylene glycol)(MPEG) and poly(L-Alanine)(PALA) were synthesized and then conjugated with folate to produce a folate receptor-targeted drug carrier for tumor-specific drug delivery. The structure of the copolymers was confirmed by (1)HNMR. The CMC values of MPEG-PALA(PLAM) and FOL-PALA-MPEG(FOL-PLAM) were 0.678 x 10(-5) mol/L and 0.864 x 10(-5) mol/L, respectively. The paclitaxel loaded micelles prepared from PLAM and FOL-PLAM both exhibited spherical shapes and nano-scale dimensions. The average diameter, encapsulation efficiency(EE), drug loading efficiency(LC) were 55nm, 80.6%, 20.2% for the PLAM micelles and 75nm, 69.7%, 17.4% for FOL-PLAM micelles. Furthermore, in vitro release study indicated that the release rate of paclitaxel from both drug-loaded micelles was slow and sustained.