氮磷比对PAMAM/DNA复合物性质的影响

Effect of N/P ratios on the characters of PAMAM/DNA complexes

目的研究氮磷比对PAMAM压缩DNA形成复合物的影响。方法采用荧光置换和荧光排除试验考察不同N/P对复合物的形成、复合物粒径和粒度分布的影响;采用琼脂糖凝胶电泳检测复合物的稳定性;采用荧光法测定复合物在MCF-7细胞内的转染效率。结果当N/P在0.5-2.5内时,复合物形成不完全,可插入或可置换的钌（Ⅱ）多吡啶类配合物[Ru（phen）2dppz]^2＋显著减少、粒径降低、PI值变大、复合物不稳定且转染效率逐渐增高;当N/P大于3.0时,复合物形成完整、粒径和PI值较小、复合物稳定且转染效率显著增高。结论当N/P大于0.5时,复合物开始形成;当N/P大于3.0时,PAMAM可以高效、稳定的压缩DNA,达到提高细胞内转染效率的目的。复合物形成完整后继续增加N/P具有提高转染效率的作用。

Objective To investigate the effect of N / P ratio on the characters of PAMAM/ DNA complexes.Methods Displacement and exclusion assays was used to investigate the influence of N / P ratio on the formation,particle size and size distribution of PAMAM/ DNA complexes; Gell electrophoresis was used to study the stability PAMAM/ DNA complexes. Fluorescencedetectionmethod was used to measure the transfection activity of PAMAM/ DNA complexes in MCF-7 cells. Results At N / P ratio between 0. 5 to 2. 5,DNA condensation was incomplete,the amount of PAMAMto displace or exclude[Ru（ phen）2dppz]2 ＋from DNA andparticle size were decreased,PI value and transfection activity were increased; At N / P ratio larger than3. 0,DNA condensation was complete,particle size and PI value were small enough,transfection activity was increased greatly. Conclusions DNA condensation is started when the N / P ratio is bigger than 0. 5. DNA condensation is completed by interaction with PAMAMand stable when the N / P ratio is bigger than 3. 0,and the transfection activity of PAMAM/ DNA complexes are increased greatly. As the N / P ratiois increased after that,the transfection of PAMAM/ DNA complexes will be increased.