Quirk Amanda, Lardner Michael J, Tun Zin, Burgess Ian J
Department of Chemistry, University of Saskatchewan , Saskatoon, SK, Canada S7N 5C9.
Canadian Neutron Beam Centre, Chalk River Laboratories , Chalk River, ON, Canada K0J 1J0.
Langmuir. 2016 Mar 8;32(9):2225-35. doi: 10.1021/acs.langmuir.5b04263. Epub 2016 Feb 23.
Surface-enhanced infrared adsorption spectroscopy (SEIRAS) and neutron reflectometry (NR) were employed to characterize ubiquinone (UQ) containing hybrid bilayer membranes. The biomimetic membrane was prepared by fusing phospholipid vesicles on a hydrophobic octadecanethiol monolayer self-assembled on a thin gold film. Using SEIRAS, the assembly of the membrane is monitored in situ. The presence of ubiquinone is verified by the characteristic carbonyl peaks from the quinone ester. A well-ordered distal lipid leaflet results from fusion of vesicles with and without the addition of ubiquinone. With applied potential, the hybrid bilayer membrane in the absence of UQ behaves in the same way as previously reported solid supported phospholipid membranes. When ubiquinone is incorporated in the membrane, electric field induced changes in the distal leaflet are suppressed. Changes in the infrared vibrations of the ubiquinone due to applied potential indicate the head groups are located in both polar and nonpolar environments. The spectroscopic data reveal that the isoprenoid unit of the ubiquinone is likely lying in the midplane of the lipid bilayer while the head has some freedom to move within the hydrophobic core. The SEIRAS experiments show redox behavior of UQ incorporated in a model lipid membrane that are otherwise inaccessible with traditional electrochemistry techniques.
采用表面增强红外吸附光谱（SEIRAS）和中子反射法（NR）对含泛醌（UQ）的混合双层膜进行表征。通过将磷脂囊泡融合在自组装于薄金膜上的疏水性十八烷硫醇单层上制备仿生膜。利用SEIRAS对膜的组装过程进行原位监测。通过醌酯的特征羰基峰验证泛醌的存在。无论是否添加泛醌，囊泡融合后都会形成排列有序的远端脂质小叶。施加电势时，不含UQ的混合双层膜的行为与先前报道的固体支撑磷脂膜相同。当膜中掺入泛醌时，电场引起的远端小叶变化受到抑制。施加电势导致泛醌红外振动的变化表明其头部基团位于极性和非极性环境中。光谱数据表明，泛醌的类异戊二烯单元可能位于脂质双层的中间平面，而头部在疏水核心内有一定的移动自由度。SEIRAS实验显示了掺入模型脂质膜中的UQ的氧化还原行为，而传统电化学技术无法实现这一点。
