Blood compatible N-maleyl chitosan-graft-PAMAM copolymer for enhanced gene transfection

To improve transfection efficiency, we prepared N-maleyl chitosan-graft-polyamidoamine (NMCTS-graft-PAMAM) copolymer. Self-assembled NMCTS-graft-PAMAM/pDNA complexes were prepared by complex coacervation method at different N/P (nitrogen to phosphate ratio) ratios. The copolymer effectively formed complexes with pDNA at lower N/P ratio (N/P ratio 1.0) than that of unmodified chitosan (N/P ratio 2.0) and the complexes were spherical with particle size of 100–150 nm. The copolymer showed significant protection of DNA from nuclease attack with lower toxicity against HeLa cell. The copolymer also showed no noticeable hemolytic effects up to 10 mg/mL indicating no detectable disturbance of the red blood cell membranes. The transfection efficiency of the copolymer was increased significantly compared to that of chitosan and reached up to 36 ± 2% at N/P ratio 7.0 which was higher than that of PEI (30 ± 3% at N/P ratio 10). Therefore, the copolymer may be a strong alternative candidate as effective nonviral vector.