Synthesis Of Amphiphilic Copolymer Poly(L-lysine)-b-Poly(L-leucine) And Its Self-assembly In Water

Amphiphilic block copolypeptides are able to self-assemble into structured aggregates,so they are used in different biomaterial applications,e.g.carriers for controlled drug release,scaffolds for tissue engineering,vehicles for gene transfer therapy,etc.This paper reported two parts contents.The first part presented the synthesis and characterization of Poly(L-benzyl -lysine) and Poly(L-leucine).Poly(L-lysine) and Poly(L-leucine) were synthesized by ring opening polymerization of Lys(Z)-NCA and Leu-NCA which were prepared by triphosgene method.Poly(L-lysine) was obtained by removal of protection group in 33%HBr solution in HAc.The two polymers were characterized by FTIR and 1H NMR.We also studied the properties of Poly(L-lysine) solution by the rheological tests.The second part presented the synthesis of amphiphilic Poly(L-lysine)-b-Poly (L-leucine) and its self-assembly behavior in water.Poly(L-benzyl-lysine) was synthesized by the same way as the first part,which was used as a macroinitiator to initiate ring opening polymerization of Leu-NCA to synthesize diblock copolymer Poly(L-benzyl-lysine)-b-Poly(L-leucine)(PZLL-b-PLeu).Amphiphilic Poly(L-benzyl-lysine)-b-Poly(L-leucine)(PLL-b-PLeu) was obtained by HBr-HAc method. The aggregation morphologies of PLL-b-PLeu in aqueous solution were observed using TEM.It was found that the diblock copolypeptide self-assembles to form micelles in water.