ROS-responsive fluorinated polycations as non-viral gene vectors

Polycation carriers hold great potential in gene therapy. However, they usually suffer from obvious cytotoxicity and unsatisfactory transfection efficiency. In this report, a series of fluorobenzene substituted and thioacetal contained polycations (TAEA-S-xF) were prepared to explore novel alternatives for safe and efficient non-viral polymeric gene vectors. The reactive oxygen species (ROS)-responsive property of thioacetal moieties together with the fluorine effect were hope to bring the vector better performance in gene delivery process. These materials could efficiently condense DNA into nanoparticles with proper size and surface potential. The structure-activity relationship of these materials was systematically investigated, and the In vitro transfection results revealed that the amount of fluorine atoms on the linkage plays important role to ensure the transfection efficiency and serum tolerance. The ROS-responsive behavior was verified by NMR, gel electrophoresis experiment and dynamic light scattering (DLS) assay. Cytotoxicity assay results also suggest that these ROS-degradable polycations show good biocompatibility in response to higher ROS level in cancer cells. Among these fluorinated polymers, the one with the most fluorine atoms showed the best transfection efficiency, which was up to 54 times higher than polyethyleneimine (PEI) 25 kDa. Mechanism studies reveal that its better performance may come from good cellular uptake and endosome escape ability.