Physico-biochemical Properties of Chitosan-poly(<i>N</i>-[3-(dimethylaminopropyl)] methacrylamide) Copolymers Synthesized as siRNA Carrier Biomaterials

In the present study, poly-(<i>N</i>-[3-(dimethylaminopropyl)] methacrylamide) (PDMAPMAAm) grafts/blocks and chitosan (Cs) backbone bearing tertiary and primary amine groups, respectively, were copolymerized by the conventional free-radical solution method to prepare novel nonviral cationic carriers covering a pH range between 4.0 and 9.0. All of the chain parameters calculated by experimental and theoretical methods indicated that with increasing KPS concentration, the structures of Cs-PDMAPMAAm (Cs/D) copolymers changed from graft to block copolymer. The constants of the Mark-Houwink-Sakurada (MHS) equation <i>K</i> and <i>a</i> were also determined to calculate the molecular weights of synthesized PDMAPMAAm and its hydrolyzed grafts. For physico-biochemical properties, FTIR, GPC, and ¹H NMR techniques, ζ-potential, particle size, hemolytic activity, buffering capacity, and cell viability measurements were performed to discuss that at least one of the Cs/D products demonstrates an acceptable transfection efficiency as <i>in vitro</i>. To investigate the cytotoxicity and gene transfection properties of Cs/D copolymers and their polyplexes with small interfering RNA (siRNA) by MTS assay on L929 and MDA-MB-231, which are healthy mouse fibroblast cells and a triple-negative human breast cancer cell line, respectively, binding capacity and serum stability by agarose gel electrophoresis, cellular uptake by confocal microscopy, and transfection efficiency of siRNA <i>in vitro</i> on the MDA-MB-231 cell line were studied.