Dual-Location Dual-Acid/Glutathione-Degradable Cationic Micelleplexes through Hydrophobic Modification for Enhanced Gene Silencing.

Gene therapy holds great promise for the treatment of acquired genetic disorders such as cancer with reduced side effects compared to chemotherapy. For gene therapy to be successful, it is crucial to develop efficient and nontoxic gene carriers to overcome the poor stability and low cellular uptake of nucleic acid-based therapeutic agents. Here, we report a new and versatile approach exploring a combination of hydrophobic modifications and dual-stimuli-responsive degradation (SRD) for controlled gene delivery with amphiphilic block copolymer-based nanocarriers. The block copolymer, synthesized by atom transfer radical polymerization, is designed with an acid-labile acetal linkage at the block junction and a pendant disulfide group in the hydrophobic block. The incorporation of labile linkages enables both disulfide-core-cross-linking and dual-location dual-acid/reduction-responsive degradation (DL-DSRD). Furthermore, the disulfide linkages integrated as hydrophobic moieties facilitate the nucleic acids to condense into nanometer-sized micelleplexes through electrostatic interactions of pendant dimethylamino groups with the anionic phosphate groups of the nucleic acids. Our preliminary results demonstrate that the DL-DSRD approach through hydrophobic modification is a robust platform in the development of gene delivery systems with enhanced colloidal stability, reduced cytotoxicity, and improved gene transfection efficiency.