Keywords: 
• PLL /
• soluble starch /
• gene carrier

Abstract: Poly-L-lysine-Starch （PLL-S） copolymer was prepared by reductive amination reaction. The PLL-S copolymer were characterized by infrared spectroscopy and nuclear magnetic resonance spectroscopy,and the molecular weights of the PLL-S were examined by gel chromatography,with a laser particle size analyzer to detect its potential. We examined the ability of the PLL to DNA-binding and degradation of the ability of anti-DNase Ⅰ using agarose gel electrophoresis. The cytotoxicity of PLL decorated with starch modified was analyzed through MTT method in 293T cells. We assayed the PLL-S transfecting plasmid DNA of capability. The results showed that the prepared PLL-S graft ratio was 2. 8%, a number average molecular weight was 60 629,potentials was 23. 7 mV. PLL-S copolymer was capable of binding to DNA,and protected DNA from the destruction of the DNase Ⅰ. The cytotoxicity of the copolymer was low enough to achieve evaluation level of one or more standard. transfection efficiency of the PLL-S copolymer was as high as （48 ± 3. 2） %. We judged that PLL-S copolymer prepared can be used as gene carriers in biomedical application by studying its performance.