Liquid-phase Synthesis And Property Study On PH-sensitive Amphiphilic Carrier--EHCO

Gene therapy is a powerful strategy to cure the diseases, especially cancer treatment, which causes more and more attention. However, obtaining efficient and safe gene delivery carries is the main bottleneck of application in gene therapy.RNA interference, as a kind of new gene therapy, can inhibite the expression of specific genes simply and efficiently.In this study, the mechanism of RNA interference, the mechanism and the existence obstacles of siRNA delivery has been discussed. There are two main challenges for efficient siRNA delivery, the target cell uptake and endosomes escape. Terefore, developping the "smart" gene delivery carries which has high controllable and high transfection efficiency becomes a major task. And pH-sensitive gene carriers received extensive attention.A novel pH-sensitive amphiphilic gene carr-EHCO, containing various proton-atable amines, dithiol groups and two lipophilic units, shows well gene transfection efficiency. In this study, we have designed to synthesis EHCO by liquid phase synthesis method, which has the advantages of high yield and expected low toxicity. And the structure of EHCO was changed from trifluoroacetate to hydrochloride. Also, in this paper, the synthesis conditions of the intermediates was optimized.Through hemolytic experiment of EHCO hydrochloride, found EHCO with no hemolytic activity at pH7.4and6.5and high hemolytic activity at pH5.4. This data explains that EHCO could alter the pH-sensitive amphiphilicity at different pH by using its head amine group with various pKa, and could selectively destruct the cell membrane to promote the siRNA endosome escape.