A convenient method for the synthesis of the amphiphilic triblock copolymer poly(L -lactic acid)-block-poly(L -lysine)-block-poly(ethylene glycol) monomethyl ether

摘要

The amphiphilic triblock copolymer PLA-b-PLL-b-MPEG is prepared in three steps through acylation coupling between the terminal amino groups of PLA-b-PZLL-NH_2 and carboxyl-terminal MPEG, followed by the deprotection of amines. The block copolymers are characterized via FT-IR, ~1H NMR, DSC, GPC, and TEM. TEM analysis shows that the triblock polymers can form polymeric micelles in aqueous solution with a homogeneous spherical morphology. The cytotoxicity assay indicates that the final triblock polymer micelles after deprotection show low cytotoxicity against Bel7402 human hepatoma cells. MPEG and PLL were introduced into the main chain of PLA affording a kind of ideal bioabsorbable polymer materials, which is expected to be useful in drug and gene delivery. Through ROP of Lys(Z)-NCA using PLA-NH _2 as initiator and subsequent coupling reaction with MPEG-COOH followed by deprotection, an amphiphilic triblock copolymer, poly(L-lactide)-block-poly(L-lysine)-block-poly(ethylene glycol), which is expected to self-assemble into spherical nanocarriers with core/corona/shell sandwich structure, is designed and synthesized.