Effect of Electric Field on Structure and Dynamics of Bilayers Formed From Anionic Phospholipids
Effect of Electric Field on Structure and Dynamics of Bilayers Formed From Anionic Phospholipids
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DOI：
10.1016/j.electacta.2014.01.035
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发表时间：
2014-11
影响因子：
6.6
通讯作者：
E. Madrid;S. L. Horswell
中科院分区：
文献类型：
--
作者：
E. Madrid;S. L. Horswell
研究了分子结构对磷脂双层膜系综结构和动力学的影响。用Langmuir-Blodgett和Langmuir-Schaeffer沉积法制备了二肉豆蔻酰磷脂酰丝氨酸（DMPS）在Au（111）表面的双层膜，并结合电化学测量和原位偏振调制红外吸收光谱（PM-IRRAS）对其进行了研究。当与由类似分子形成的那些相比时，DMPS双层具有相对大的电容，并且这归因于双层内的高溶剂含量，这是由带负电荷的脂质头基的溶剂化的需要引起的。红外光谱表明，分子系综是在凝胶状态，与扩展和有序的烃链，类似的双分子层的二肉豆蔻酰磷脂酰乙醇胺（DMPE）分子，这是相似的形状。红外光谱还表明，与DMPE相比，DMPS的头基是非常强的水合的，并且具有更高的流动性。这种更高的流动性允许在所施加的电场的影响下的分子的重新取向：观察到头部基团和烃尾部基团的重新取向。因此，在一个系综中分子的形状和电荷对它们的结构和动力学都有很大的影响，在外部施加电场的存在下。
The effect of molecular structure on ensemble structure and dynamics of phospholipid bilayers has been investigated. Bilayers of dimyristoyl phosphatidylserine (DMPS) supported on Au(111) surfaces were prepared by Langmuir-Blodgett and Langmuir-Schaeffer deposition and studied with a combination of electrochemical measurements andin situPolarisation Modulation Infrared Reflection Absorption Spectroscopy (PM-IRRAS). DMPS bilayers have relatively large capacitance when compared with those formed from similar molecules and this is attributed to a high solvent content within the bilayer, resulting from the need for solvation of the negatively charged lipid headgroups. Infrared spectra show that the ensemble of molecules is in a gel state, with extended and ordered hydrocarbon chains, similarly to bilayers of dimyristoyl phosphatidylethanolamine (DMPE) molecules, which are of similar shape. The infrared spectra also show that, in contrast to DMPE, the headgroups of DMPS are very strongly hydrated and have higher mobility. This higher mobility allows the re-orientation of the molecules under the influence of an applied electric field: re-orientation both of headgroups and hydrocarbon tail groups is observed. Thus the shape and charge of the molecules in an ensemble have a strong influence on both their structure and dynamics in the presence of an externally applied electric field.