Chitosan modified by γ-ray-induced grafting of poly(tributyl-(4-vinylbenzyl) phosphonium) as the biosafe and high-efficiency gene carrier
The development of gene carriers with high delivery efficiency and enough biosafety to replace the current viral vectors and cationic liposomes has long been a key project to achieve the practical application of gene therapy. As an abundant natural polymer, chitosan (CS) possesses incomparable high biocompatibility. However, when it is used as the gene carrier, the gene transfection efficiency is rather disappointing. Herein, we prepared a novel chitosan derivative, poly(tributyl-(4-vinylbenzyl) phosphonium) grafted CS (CS-P), via γ-ray radiation induced grafting copolymerization of tributyl-(4-vinylbenzyl) phosphonium in an acidic solution of CS. The CS-P could combine with pEGFP through a complex coacervation method to form pEGFP-loaded CS-P complex particles with a size of about 150 nm and a high positive zeta potential of 41.7 ± 6.1 mV. The agarose gel electrophoresis and MTT assay show the pEGFP-loaded CS-P particles has an excellent biosecurity, superior to pEGFP-loaded unmodified CS particles. The in vitro and in vivo gene transfection experiments based on HeLa cells confirmed that pEGFP loaded in CS-P particles exhibits much higher gene transfection efficiency than that loaded in the unmodified CS. This work provides not only a new way to modify CS with quaternary phosphonium, but also a useful and feasible way to obtain new CS-based gene vectors with high gene transfection efficiency and biosecurity for potentially practical clinic applications.