Synthesis of polypeptide bearing 1,4-dithiane pendants for ROS-responsive drug release

Stimuli-re sponsive polypeptides have been intensively investigated fo r controlled drug release,owing to their favorable biocompatibility and biodegradability.In this work,we designed and synthesized a new kind of polypeptide bearing 1,4-dithiane pendants for reactive oxygen species(ROS)-responsive drug release.The polypeptide-based block copolymer was facilely synthesized by ring-opening polymerization(ROP)of 1,4-dithian-substituted L-glutamate N-carboxyanhydride(DTG-NCA)monomer using an amino-terminated poly(ethylene glycol)methyl ether(mPEG-NH2)as the macro molecular initiator.The resulta nt block copolyme r,mPEG-b-PDTG,could self-assemble into unifo rm micelles in aqueous medium owing to its amphiphilic structure.Then,the H2 O2-triggered oxidation behaviors of the mPEG-b-PDTG micelles were studied by dynamic light scattering(DLS),FT-IR and turbidimetric assay.It was revealed that the oxidation of thioether into sulfoxide in the side chains would result in disassembly of the micelles.Furthermore,the ROS-responsive drug release behavior of the mPEG-b-PDTG micelles was verified by using Nile Red as a model drug.MTT assay also proved that mPEG-b-PDTG was non-toxic in B16 F10 and L929 cells.Therefore,such a new class of oxidation-responsive polypeptide might provide a promising platform for ROS-responsive drug delivery.