中文摘要：

目的采用精氨酸优化壳聚糖一硬脂酸聚合物／DNA转染条件，以提高细胞转染效率，并探讨精氨酸对增强转染效率的机制。方法共孵育法制备聚合物／精氨酸／pDNA三元复合物纳米粒，原子力显微镜观察复合纳米粒形态，动态光散射法测定其粒径大小；凝胶电泳分析精氨酸的加入对糖脂聚合物密接和保护pDNA能力的影响；萤火虫荧光素酶定量法研究精氨酸对糖脂聚合物／DNA复合物细胞转染效率的影响。结果糖脂聚合物、精氨酸和pDNA3者混合后可形成稳定的复合物纳米粒，粒径大小为180nm左右。凝胶电泳分析结果表明，复合物具有密接和保护pDNA的能力。体外细胞转染实验发现，添加精氨酸后，复合物的细胞转染水平提高了2．09倍，且不影响细胞毒性。结论精氨酸可显著提高糖脂聚合物介导的基因转染效率，其可能的机制在于精氨酸有助于促进复合纳米粒进入靶细胞后质粒DNA从纳米粒中的释放。

英文摘要：

OBJECTIVE To optimize the transfection efficiency of chitosan oligosaccharide grafted stearic acid （CSOSA）/pDNA Using arginine, and investigate the role of arginine for enhancement of transfection efficency in vitro. METHODS CSOSA/arginine/ pDNA nanoparticles were prepared by a complex coacervation technique. The morphology of the nanoparticles was examined by atomic force microscope. The particle size and zeta potential were determined using Zetasizer. The ability of CSOSA to form complex with pDNA and protect the DNA from degradation by DNase were confirmed by gel retardation. The transfection efficiency of CSOSA/arginine/ pDNA complex was determined in terms of luciferase activity of the protein expressed. RESULTS CSOSA, arginine and plasmid DNA could form stable complex nanoparticles with a particle size of about 180 rim, which was smaller than that of CSOSA/pDNA. Gel electrophoresis experiments revealed that the complex could condense plasmid DNA as well as protect DNA from enzymolysis of DNase. It was found that the in vitro transfection efficiency of ternary complexes increased 2. 09-fold compared with the CSOSA/pDNA complexes, and the cytotoxicity of ternary complex was as low as that of CSOSA/pDNA. Moreover, the ternary complex nanoparticles showed much lower cytotoxicity and matched transfection efficiency in comparison with LipofectamineTM 2000. CONCLUSION The transfection efficiency of CSOSA/pDNA complexes is significantly improved in the presence of arginine. The possible mechanism of arginine-mediated enhancement of transfection efficiency is that arginine can promote the release of DNA from the complexes when uptaken into thrget cells.