Galactosylated Poly(Vinyldiaminotriazine) Copolymer-Based Vector For Gene Transfection

In this thesis, galactose modified poly(2-vinyl-4,6-diamino-1,3,5-triazine) (PVDTLac)/PVDT copolymer was prepared. The characteristics of PVDTLac/DNA complexes formed via complementary hydrogen bond and gene transfection mediated by this nonviral vector were investigated. The main work includes three parts as follows:1) A PVDTLac-PVDT copolymer was prepared by copolymerization of galactose modified 2-vinyl-4,6-diamino-1,3,5-triazine(VDT) with VDT monomer itself. The water solubility of the copolymer was much better than PVDT homopolymer. The results of 1H NMR confirmed that galactose groups had been coupled with triazine rings.2) The properties of the copolymer vector/plasmid DNA complexes were investigated. The complexes with different vector/plasmid DNA weight ratios were prepared. The electrophoresis and transmission electron microscope(TEM) demonstrated how the vectors influenced the shape and size of the plasmid DNA. The agarose gel electrophoresis indicated that PVDTLac-PVDT vector was capable of condensing DNA efficiently. PVDTLac-PVDT(1:2) could condense DNA with lower weight ratio, because of richer amino groups. The morphology of the complexes, plasmid DNA and the vectors was observed by TEM. The morphology of the complexes depended on the weight ratio of vectors, showing globules, toroids or large size of aggregates. In a relatively small weight ratio, the vectors were unable to encapsulate DNA firmly, with existence of loose DNA structure. As the weight ratio increased, DNA was condensed gradually. When the ratio was close to the optimal ratio, the complexes assumed a toroid-like shape. If the ratio was further enhanced, the complexes appeared dispersed toroid or globules. The distribution of the particle diameter observed by TEM demonstrated that the diameter of complexes tended to decrease as the ratio was further increased when the weight of the vector reached a certain value.3) Two vectors with different ratios were used to transfer PGL3 into COS-1 cells. The transfection efficiency was determined by the luciferase activities. The results revealed that PVDTLac could transfer PGL3 into COS-1 cell lines. The transfection efficiency of PVDTLac vector was 52～178 times higher than that of naked DNA; while PVDTLac could reach 50%~74% Exgen 500 transfection level.