LAUSR

A novel biotinylated chitosan‐graft‐polyethyleneimine (Bio‐Chi‐g‐PEI) copolymer was synthesized and evaluated as a nonviral gene delivery carrier for improvement of the transfection efficiency, endosomal escape, and targeted gene delivery of a plasmid encoding green fluorescent protein N1 (pEGFP‐N1) into two different biotin‐overexpressing cell lines including HeLa and OVCAR‐3 cells. The structure of the obtained copolymers was confirmed by 1H nuclear magnetic resonance (1H NMR) and Fourier transform infrared spectroscopy. Physicochemical properties of the Bio‐Chi‐g‐PEI/plasmid DNA (pDNA) complexes such as complex stability, size, zeta potential, and their morphology were investigated at various weight ratios of copolymer to pDNA. Bio‐Chi‐g‐PEI copolymers could effectively condense pDNA into small particles with average diameters less than 164 nm and the zeta potential of +34.8 mV at the N/P ratio of 40/1. As revealed by flow cytometry, Bio‐Chi‐g‐PEI/pDNA complexes had lower cytotoxicity than that of PEI 25 kDa/pDNA complexes in both cell lines. In vitro experiments revealed that the Bio‐Chi‐gPEI/pDNA complexes not only had much lower cytotoxicity, but also displayed higher transfection efficiency than that of PEI 25kDa/pDNA complexes. High percentage of cancer cells was successfully transfected by Bio‐Chi‐g‐PEI/pDNA and properly expressed GFP protein. This study indicates that this copolymer complex can be a promising gene delivery carrier.