Novel glycol chitosan-based polymeric gene carrier synthesized by a Michael addition reaction with low molecular weight polyethylenimine

• We present new method for synthesis of glycol chitosan-graft-polyethylenimine.
• The polymer assembles with plasmid DNA into nanorods.
• The polymer shows increased buffering capacity compared to native glycol chitosan.
• We evaluate the transfection efficiency and cytotoxicity of the polymer in vitro.

A glycol chitosan-based polymer that spontaneously assembles with plasmid DNA into nanorods was evaluated as a non-viral vector for gene delivery. Glycol chitosan–methyl acrylate-polyethylenimine (GMP) was synthesized by grafting polyethylenimine onto glycol chitosan via amidation after Michael addition using methyl acrylate. Gel retardation and PicoGreen assay experiments showed complete complex formation with plasmid DNA. GMP/pDNA complexes were characterized using biophysical techniques and were found to be positively charged rod-shape structures with widths in the nanometer scale and lengths in the micrometer scale. Transfection efficiency and cytotoxicity of GMP polymer was evaluated in human epithelial ovary carcinoma (HeLa) cells, human embryonic kidney 293 (HEK293) cells, and human hepatocellular liver carcinoma (HepG2) cells, in comparison to high molecular weight polyethylenimine, a commonly used transfection reagent. Intracellular polymer uptake was compared and confirmed by confocal microscopy. The results demonstrate that GMP, a hybrid polymer of glycol chitosan grafted with branched polyethylenimine, may serve as a promising vehicle for efficient gene delivery.