| 帅浪,宋江闯,尚亚卓,刘洪来.化学通报,2015,78(2):146-152. |
| 阳离子Gemini表面活性剂12-3-12与DNA在模拟体液中的相互作用研究 |
| Interaction between Gemini Surfactant(12-3-12) and DNA in simulated body fluid |
| 投稿时间：2014-05-15 修订日期：2014-06-06 |
| DOI： |
| 中文关键词: 模拟体液 Gemini表面活性剂 DNA 相互作用 分子动力学模拟 |
| 英文关键词:simulated body fluid (SBF) Gemini surfactant DNA interaction molecular dynamics simulation |
| 基金项目:国家自然科学基金项目(21173079、91334203)资助 |
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| 中文摘要: |
| 采用紫外透射光谱、透射电子显微镜(TEM)、原子力显微镜(AFM)、圆二色光谱(CD)等方法探讨了阳离子Gemini表面活性剂C12H25N (CH3)2-(CH2)3-(CH3)2N C12H25?2Br- (12-3-12)与DNA在模拟体液（SBF）中的相互作用。研究结果表明，模拟体液中较高反离子浓度不但屏蔽了DNA和12-3-12之间静电吸引作用而且促进了表面活性剂12-3-12聚集体的产生和生长，导致低盐条件下体系中出现的沉淀溶解现象的消失。模拟体液中DNA与12-3-12之间存在强烈的相互作用；随着表面活性剂12-3-12的加入，表面活性剂分子在DNA链周围聚集，类网络结构的DNA逐渐变为类似于串珠的复合物，随后出现尺寸较大的类球形复合物以及较大复合物与较小表面活性剂聚集体共存的现象。CD光谱结果显示，模拟体液中12-3-12可以诱导DNA的构象发生改变，由自然的B构型变成高度致密的ψ相。分子动力学模拟的离子液体中表面活性剂与带相反电荷聚电解质的相互作用过程及模式与实验结果吻合良好。模拟结果也表明，模拟体液中较高的反离子浓度提高了聚电解质的可压缩程度导致相同条件下模拟体液中聚电解质均方回旋半径远小于稀盐水溶液（10mMNaBr）体系中聚电解质均方回旋半径。较强的离子强度不但导致体系中聚电解质和带相反电荷表面活性剂之间的相互作用可能存在“假饱和”现象，而且也造成体系中表面活性剂在聚电解质周围聚集数显著提高。 |
| 英文摘要: |
| Interactions between cationic Gemini surfactantC12H25N (CH3)2-(CH2)3-(CH3)2N C12H25?2Br- (12-3-12) and DNA in simulated body fluid were investigated using UV-Vis spectroscopy, transmission electron microscope (TEM), atomic force microscope (AFM) and circular dichroism (CD). Higher anti-ion concentration in SBF not only shield electrostatic attraction between DNA and 12-3-12, but also promote the emergence and growth of surfactant aggregates, preventing precipitate dissolution which usually appears at lower salt condition. There is strong interaction between DNA and 12-3-12, the surfactant molecules aggregate around the DNA chains with the addition of surfactant and correspondingly the DNA with network structures turn into complexes with necklace-like structures because of the combination with surfactants. Subsequently, the bigger spherical complexes and the coexistence of bigger complexes and smaller surfactant aggregates are observed in the present system. Circular dichroism (CD) spectra shows that DNA structure turns into condensed ψ phase from typical B conformation because of its interaction with 12-3-12. The results obtained by molecular dynamics simulations are coincide well with the experimental results. Higher anti-ion concentration in SBF increases compressibility of polyelectrolyte, which leads to smaller mean square radius of gyration than that in the dilute salt solution (10mM NaBr). It seems that the stronger ionic strength in SBF not only leads to "false saturation" phenomenon between surfactant and oppositely charged polyelectrolyte, but also increases surfactant’s aggregation number around polyelectrolyte significantly. |
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