本项目以课题组前期构建的AGM-CBA作为基础载体，通过构建含有不同数量的胍基、二硫键和烷基侧链长度的PAAs（聚氨基胺类）类共聚物，旨在考察聚合物基因载体的功能基团与转染效率之间的构效关系，并在翻译和转录水平上对基因／载体复合物可能影响转染效率的环节进行系统考察，以期筛选出影响聚合物基因递送能力的关键结构，为进一步探索PAAs类基因载体的构建策略提供系统的理论指导和实验依据。利用多种技术（DLS、AFM、FCM、FM等）对构建的载体以及基因/载体复合物的理化性质、生物学指标、摄取和转运机制进行研究。应用“伪质粒参与”实验考察聚合物中二硫键的关键作用；以激光扫描共聚焦显微镜为主要方法，考察聚合物中胍基的核定位作用；应用CIDIQ（共聚焦成像偶联三维重构积分定量分析法）和FRAP（光漂白荧光恢复实验）两种手段，探索基因/载体复合物在细胞核内的分布。

Based on the AGM-CBA that has been built by our group, this project aims to investigate the structure-function correlation between functional groups and transfection efficiency of poly(amido amine)s (PAAs), by synthesizing PAAs with different amount of guanidinium group or disulfide bond or different alkyl chain lengths. We also intend to systematically investigate the key factors that may affect the transfection efficiency of polyplexe (polymer/DNA complexes) at the level of transcription and translation, in order to screen the key structure influencing the gene delivery capacity of polymers and provide systematic theory guidance and experimental evidence for further PAAs construction. Various experimental techniques, such as DLS、AFM、FCM、FM, will be used to study the physical and chemical properties, biological indicators, and transport mechanisms of polymers and polyplexes. Through these methods, we hope to find out the regularity between chemical structures and biological characteristics. “Fake plasmid participation” experiment will be designed to the key function of disulfie bond in the polymers. Laser scanning confocal microscope (LSCM) will be applied to confirm the nuclear localization ability of guanidinium group in the polymers. Finally, novel methods of CIDIQ (Confocal Image-assisted.3-Dimensionally Integrated Quantification) and FRAP (Fluorescence Recovery after Photo bleaching) will be used to discover the distribution of polylexe in the cell nucleus.