Department of Chemistry, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
Langmuir. 2010 Jan 19;26(2):1057-66. doi: 10.1021/la902325n.
A film of oriented bilayers containing a mixture of gramicidin and dimyristoylphosphatidylcholine (DMPC) has been deposited on a fused-silica window coated with a 10 nm thick gold layer. The thin layer of gold allows the application of an electric potential across the film and the study of its influence on the structure and integrity of the bilayers. Electrochemical measurements, ellipsometry, and far-UV circular dichroism (CD) were employed to characterize the properties of the film of bilayers as a function of the potential applied to the gold electrode. For potentials across the film that are within the range approximately +300 to -150 mV the oriented film of bilayers is stable, and no change in the CD spectra of gramicidin molecule is observed. At more negative potentials, an increase in the film thickness and water content measured by ellipsometry indicated that the film swells and incorporates water, which causes a change in the circular dichroism spectrum of gramicidin molecules in the film. This transformation was interpreted as a change in the average orientation of gramicidin molecules within the film due to a decrease in the ordering of the molecules upon swelling.
一层取向的双层膜，其中含有短杆菌肽和二肉豆蔻酰磷脂酰胆碱（DMPC）的混合物，已沉积在涂有 10nm 厚金层的熔融石英窗上。这层薄金允许在膜上施加电势，并研究其对双层膜结构和完整性的影响。电化学测量、椭圆偏振法和远紫外圆二色性（CD）被用来表征双层膜的性质作为施加到金电极的电势的函数。对于跨膜的电势在大约+300 到-150mV 的范围内，取向的双层膜是稳定的，并且没有观察到短杆菌肽分子的 CD 光谱发生变化。在更负的电势下，椭圆偏振法测量的膜厚度和含水量的增加表明膜发生了膨胀并包含了水，这导致了膜中短杆菌肽分子的圆二色性光谱发生了变化。这种转变被解释为由于膨胀导致分子有序性降低，从而导致膜中短杆菌肽分子的平均取向发生变化。
