| Vinyldiaminotriazine/N-Isopropylacrylamide copolymers(PVDT-co-PNIPAAm) were prepared in this work. The characteristics of PVDT-co-PNIPAAm/DNA complexes formed via complementary hydrogen bond and gene transfection mediated by this nonviral vector were investigated. These copolymers were synthesized through conventional radical random polymerization, and water-soluble fractions were collected. The formation of the copolymers was confirmed by FTIR. Results from GPC showed that the molecular weight was very low. The molar ratios of copolymers and the concentrations of any vector solutions were determined via the ABS value at 260nm of the polymer solutions. Copolymer vector/plasmid DNA complexes with different weight ratios were prepared. The agarose gel electrophoresis indicated that PVDT-co-PNIPAAm vector was capable of condensing DNA efficiently, and the electrophoresis pattern also exhibited characteristics of hydrogen bonding type. In TEM images, depending on the complexing ratios, the morphology of the complexes assumed globules or large size of aggregates, which resembled DNA condensation induced by cationics. In vitro transfection revealed that PVDT-co-PNIPAAm vectors could transfer pGL3 into COS-1 cell line. The transfection efficiency of copolymer vector was 30～66 times higher than that of naked DNA; while one order lower than that of commercial vector ExGen 500. The transfection efficiency was enhanced to 1.7～4.5 folds via altering the cell culture temperature during transfection as compared with constant temperature culture. MTT experiment indicated that the copolymer vectors had very low cytotoxicity.
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