Studies On Folate-Modified Chitosan Targeting Vector For Gene Delivery

At present, more and more countries and research institutions have atta-ched importance to the Chitosan as a new Non-viral gene vector. In recent years, folate-folate receptor targeting is a new Popular Anti-tumor mechanis-ms. Targeted gene is targeting transported via the folate receptor, based on the fact that folate receptor can be overexpressed on the surface of some kinds of tumor cells but scarcely expressed on normal cells. Folate can be selected to chemically modify the Chitosan to improve the targeting ability and the transfection efficiency of the gene transfection.This experiment is completed by the acylation of the amine group on the chitosan. Condensing agent is reacted firstly with the folate to prepare the acti-ve intermediate. And then the folate-coupled chitosan (FA-CS) is pr-epared by the reaction of the active intermediate with the amine group on t-he chitosan. The different amount of the folate to the chitosan is prepared successfully. The FA-CS is verified by the Infrared Spectroscopy. The amou-nt of the folate in each of the chitosan is mensurated by the UV Spectroph-otometry. The pEGFP-C1 is selected as the reporter gene. The (FA-CS)-DNA nanometer grain and the CS-DNA nanometer grain are prepared by the co-mplex coacervation. The morphology of the nanometer grain is observed by the transmission electron microscopy. The protection ability of the nanometer grain to DNA is checked by DNaseâ… digestive experiment. It is transfected to HeLa cell. The targeting ability and the transfection efficiency of the (FA-CS)-DNA nanometer grain as a vector in gene transference is compared to the CS-DNA nanometer grain by fluorescence microscope.The infrared spectra of the FA-CS show that the FA-CS is prepared su-ccessfully. And the amount of the folate in each of the chitosan is approxi-mately three,ten,twenty,thirty. The (FA-CS)-DNA nanometer grain solute-on and the CS-DNA nanometer grain solution are homogeneous, stable and clear. The results of the transmission electron microscopy show that the nan-ometer grain is the same size, non-adhesive and distributed evenly. It is sph-erical or nearly spherical. The (FA-CS)-DNA nanometer grain is approximat-ely 120nm in diam-eter and the CS-DNA nanometer grain is approximately 140nm in diameter. The results of the DNaseâ… digestive experiment show th-at both the (FA-CS)-DNA nanometer grain and the CS-DNA nanometer grain can protect DNA we-ll. The results of the fluorescence microscope show t-hat the pEGFP-C1 can be transported to HeLa cell and expressed by both t-he (FA-CS)-DNA nanometer grain and the CS-DNA nanometer grain. But the targeting ability and the tran-sfection efficiency of the (FA-CS)-DNA nano-meter grain which the amount of the folate in each of the chitosan is appro-ximately ten and twenty are better.