Study Of Polyplex For Efficient And Non-toxic Gene Delivery

Cationic polymers are important non-viral gene vectors which have achieved huge development during the past decades.Compared with the viral vectors,cationic polymers represent a series of advantages including non-immunogenic,not oncogenic and easy to produce.But the paradox between transfection efficiency and cell toxicity is always a hindrance for their applications:(1)cationic polymers with high transfection efficiency are highly cytotoxic;(2)the safe cationic polymers are always low efficient in gene transfection.Hence,how to overcome this paradox is an important scientific problem.Here,we proposed a solution:to construct a supramolecular polymer system as a gene vector with high efficiency and low toxicity based on the Polyamidoamine(PAMAM)dendrimers.To this end,the following two strategies are proposed:(1)Develop a core-shell polyplex using a high generation dendrimer as the core polymer to condense plasmid DNA and a low-molecular-weight cationic polymer as the shell polymer.PAMAM dendrimers of different high generations as core polymers and low-molecular-weight linear polyethylenimine(LPEI),branched polyethylenimine(BPEI)and G2 PAMAM dendrimer as shell polymers were tested.Among them,polyplex composed of G8 PAMAM dendrimer and LPEI represented very high transfection efficacy and low toxicity.The mechanism investigation indicated that the core-shell structure enabled an easy release of DNA in cytoplasm.(2)Cross-linking strategy.G2 PAMAM dendrimer was cross-linked with fullerene C60,and we got a kind of uniform particles with high transfection efficiency and low toxicity.The mechanism investigation indicated that the cross-linked products enhanced DNA's cell uptake.In summary,based on cationic PAMAM dendrimer,we developed two ingenious approaches to achieve two kinds of gene transfection vectors with both high efficacy and low toxicity:G8/LPEI/DNA and C60-G2/DNA.We will further evaluate their in vivo transfection efficacy and explore the photodynamic therapy of C60-G2/DNA,and we hope these results can promote the clinical application of gene therapy combined with photodynamic therapy.