Facile synthesis of poly(disulfide)s through one-step oxidation polymerization for redox-responsive drug delivery

Poly(disulfide)s-based systems with repetitive disulfide bonds in their backbones are emerging as promising tumor microenvironment responsive platforms for drug delivery. However, complicated synthesis and purification processes have restricted their further application. Herein, we developed redox-responsive poly(disulfide)s (PBDBM) by one-step oxidation polymerization of a commercially available monomer, 1,4-butanediol bis(thioglycolate) (BDBM). PBDBM can self-assemble with 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-poly(ethylene glycol)(3400) (DSPE-PEG(3.4k)) by the nanoprecipitation method and be formulated into PBDBM NPs (sub 100 nm). It can also be loaded with docetaxel (DTX), a first-line chemotherapy agent for breast cancer, to form DTX@PBDBM NPs with a loading capacity of 6.13%. DTX@PBDBM NPs with favorable size stability and redox-responsive capability exhibit superior antitumor activity in vitro. In addition, owing to the different glutathione (GSH) levels in normal and tumor cells, PBDBM NPs with disulfide bonds could synergistically increase intracellular ROS levels, further inducing apoptosis and cell cycle arrest in the G2/M phase. Moreover, in vivo studies revealed that PBDBM NPs could accumulate in tumors, suppress 4T1 tumor growth, and significantly attenuate the systemic toxicity of DTX. Thus, a novel redox-responsive poly(disulfide)s nanocarrier was successfully and facilely developed for cancer drug delivery and effective breast cancer therapy.