Effects of molecular weight and pyridinium moiety on water-soluble chitosan derivatives for mediated gene delivery

► Chitosan containing pyridinium moiety was synthesized as a model DNA vector. ► Nanopolyplex based on chitosan derivative ionically bonded to DNA was obtained. ► Transfection efficiency depended on MW, quaternary ammonium type and N/P ratio. ► Enhancement in transfection efficiency and reduction of cytotoxicity was achieved.