Tailor-made ternary nanopolyplexes of thiolated trimethylated chitosan with pDNA and folate conjugated cis-aconitic amide-polyethylenimine for efficient gene delivery

To overcome the different extra-/intracellular barriers in gene delivery, tumor-targeted and pH/redox-responsive ternary polyplexes with charge-conversional properties were prepared through a modular self-assembly strategy. Firstly, the thiolated trimethylated chitosan (TMC-SH) was synthesized to crosslink and condense pDNA through electrostatic interaction and disulfide formation, which obtained the TMC-SS/pDNA binary polyplexes with redox-responsive gene release. To further endow the binary polyplexes with tumor targeting and endo/lysosomal pH-triggered charge-reversal properties, a folate conjugated cis-aconitic amide-polyethylenimine (FA-PEI-AcO) was synthesized to shield the positive TMC-SS/pDNA, generating the FA-PEI-AcO/TMC-SS/pDNA ternary polyplexes with a size of similar to 190 nm and negative surface-charges. The.-potential of the polyplexes was stable at physiological pH and increased rapidly from -14 mV to + 20 mV at pH 5.5 (endo/lysosomal pH) due to the breakages of acid-liable amide bonds and the subsequent de-shielding of FA-PEI-AcO layers, which might benefit the endo/lysosomal escape of the polyplexes. Afterward, the polyplexes could redox-responsively release gene at higher intracellular concentrations of glutathione. By taking advantage of such multi-responses, significantly enhanced transfection efficiency was achieved in vitro in Hela cells for the ternary polyplexes. These results suggested that the newly developed polyplexes had potential application for gene delivery. (C) 2019 Elsevier B.V. All rights reserved.