Wettig Shawn D, Badea Ildiko, Donkuru McDonald, Verrall Ronald E, Foldvari Marianna
School of Pharmacy, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1.
J Gene Med. 2007 Aug;9(8):649-58. doi: 10.1002/jgm.1060.
Increases in DNA transfection efficiencies for non-viral vectors can be achieved through rational design of novel cationic building blocks. Based on previous results examining DNA condensation by polyamines, novel gemini surfactants have been designed that incorporate aza or imino substituents within the spacer group in order to increase interactions with DNA and potentially improve their DNA transfection ability.
Transfection efficiencies and cell toxicity of gemini nanoparticles constructed from plasmid DNA, gemini surfactant, and a neutral lipid were measured in COS7 cells using a luciferase assay. Structural properties of nanoparticles were examined by using circular dichroism, particle size, zeta potential, and small-angle X-ray scattering (SAXS) measurements.
The incorporation of aza and imino substituents within the spacer group was observed to enhance the transfection ability of gemini surfactants. Incorporation of an imino group in the structure of the 1,9-bis(dodecyl)-1,1,9,9-tetramethyl-5-imino-1,9-nonanediammonium dibromide surfactant (12-7NH-12) resulted in a statistically significant (p < 0.01) 9-fold increase in transfection compared to an unsubstituted gemini surfactant and a 3-fold increase compared to the corresponding aza-substituted compound. A pH-dependent transition in size and zeta potential was observed to occur at pH 5.5 for complexes formed from the 12-7NH-12 compound. SAXS results show weakly ordered structures and the presence of multiple phases.
The incorporation of a pH-active imino group within the spacer of the gemini surfactant results in a significant increase in transfection efficiency that can be related to both pH-induced changes in nanoparticle structure and the formation of multiple phases that more readily allow for membrane fusion that may facilitate DNA release.
通过合理设计新型阳离子构建模块，可以提高非病毒载体的DNA转染效率。基于先前关于多胺对DNA凝聚作用的研究结果，已设计出新型双子表面活性剂，其在间隔基团中引入了氮杂或亚氨基取代基，以增强与DNA的相互作用，并有可能提高其DNA转染能力。
使用荧光素酶测定法在COS7细胞中测量由质粒DNA、双子表面活性剂和中性脂质构建的双子纳米颗粒的转染效率和细胞毒性。通过圆二色性、粒径、zeta电位和小角X射线散射（SAXS）测量来研究纳米颗粒的结构特性。
观察到在间隔基团中引入氮杂和亚氨基取代基可增强双子表面活性剂的转染能力。在1,9-双（十二烷基）-1,1,9,9-四甲基-5-亚氨基-1,9-壬二铵二溴化物表面活性剂（12-7NH-12）的结构中引入亚氨基，与未取代的双子表面活性剂相比，转染率有统计学意义的显著提高（p < 0.01），提高了9倍；与相应的氮杂取代化合物相比，提高了3倍。观察到由12-7NH-12化合物形成的复合物在pH 5.5时发生粒径和zeta电位的pH依赖性转变。SAXS结果显示结构有序性较弱且存在多个相。
在双子表面活性剂的间隔基团中引入pH活性亚氨基可显著提高转染效率，这可能与pH诱导的纳米颗粒结构变化以及多个相的形成有关，多个相更易于实现膜融合，从而可能促进DNA释放。
