Evaluation of disulfide bond-conjugated LMWSC-g-bPEI as non-viral vector for low cytotoxicity and efficient gene delivery

For efficient gene delivery, non-viral vectors should have high cellular uptake, excellent endosomal escape, and the ability to rapidly release the gene into the cytoplasm. Here, we developed a disulfide bond-conjugated bioreducible LMWSC-g-bPEI (LCP) composed of low molecular-weight water soluble chitosan (LMWSC), bPEI, and cystamine (Cys). The developed LCP had advantages such as low toxicity, great endosomal escape, and rapid release of pDNA into the cytoplasm. The polyplexes with LCP showed higher uptake into the nucleus and greater transfection efficiency than that without disulfide bond. Moreover, LCP polymer and polyplexes with LCP indicated lower cytotoxicity than bPEI 25 kDa. In addition, a gel retardation assay and particle size were analyzed to demonstrate the reduction-sensitive gene delivery system. Besides, intracellular uptake pathway of polyplexes was investigated by various endocytosis inhibitor and confirmed to internalization into cell via macropinocytosis. These results suggest that bioreducible LCP is a superb non-viral vector for efficient gene delivery.