Nature of the Interaction between a Peptidolipid Langmuir Monolayer and Paraoxon in the Subphase

详细信息    查看全文

• 作者：Chengshan Wang ; Jiayin Zheng ; Osvaldo N. Oliveira Jr. ; Roger M. Leblanc
• 刊名：Journal of Physical Chemistry C
• 出版年：2007
• 出版时间：May 31, 2007
• 年：2007
• 卷：111
• 期：21
• 页码：7826 - 7833
• 全文大小：268K
• 年卷期：v.111,no.21(May 31, 2007)
• ISSN：1932-7455

文摘

Surface potential and Infrared Reflection-absorption spectroscopy (IRRAS) measurements have been usedto investigate the interaction between a peptidolipid (stearoyl-Phe-Trp-Ser-His-Glu) Langmuir monolayerand paraoxon aqueous solution as subphase. The molecular recognition in this system involved - interactionsbetween the nitrobenzene group of paraoxon and aromatic groups in the peptidolipid. Of particular importancewas the dependence of the surface potential on the concentration of paraoxon. Effects were practically negligiblefor 1.0 × 10^-5 and 1.0 × 10^-6 M paraoxon concentrations, but the Langmuir monolayer surface potentialdropped due to the interaction with paraoxon at a concentration equal or higher than 1.0 × 10^-4 M. At 1.5× 10^-3 M, the surface potential-area (V-A) isotherm for the peptidolipid displayed an unusual shape,with an almost constant, near-zero surface potential during the monolayer compression. This was interpretedon the basis of IRRAS results as being due to reorientation of the benzene ring of paraoxon, which changedfrom parallel to the air-water interface in the absence of a monolayer to a tilted orientation upon interactingwith the peptidolipid monolayer.