Chitosan-graft-polyethylenimine with improved properties as a potential gene vector

A novel chitosan-graft-polyethylenimine (CHI-g-PEI) copolymer with biocleavable disulfide linkages between chitosan chains and PEI grafts was synthesized, characterized, and examined as a potential nonviral gene vector. The chemical structure of the obtained product was characterized by 1H NMR, FTIR and Raman spectroscopy, respectively. Agarose gel retardation assay, dynamic light scattering, and scanning electron microscopy experiments revealed that CHI-g-PEI had a good ability of condensing plasmid DNA into spherical nanoparticles in the size range of 200–300 nm. In the imitative physiological environment the polymer/pDNA complexes are relatively stable, meanwhile, an efficient release of pDNA was detected in the presence of 25 mM DTT, mimicking the intracellular reductive environment. These results show that the bioreducible CHI-g-PEI copolymer, thus obtained, can be used as a promising nonviral gene carrier due to its excellent properties.