Synthesis of N-methylene phosphonic chitosan (NMPCS) and its potential as gene carrier

N-Methylene phosphonic chitosan (NMPCS), an amphiphilic macromolecule with powerful chelating ability of Ca2+ ions, was synthesized and characterized. The physicochemical properties of NMPCS and the interactions between NMPCS and plasmid DNA were investigated by FTIR, 13C NMR, X-ray, agarose gel electrophoresis retardation assay, atomic force microscopy (AFM) and circular dichroism (CD). The results suggest that at charge ratio 2:1 or above, DNA could be completely entrapped and spherical complexes with mean size of 80–210 nm were formed. Taking HeLa as host cell, luciferase expression mediated by NMPCS improved about 100 times compared to the expression mediated by chitosan.