Surface spectroscopy and microscopy studies of functional molecular films at electrified interfaces

带电界面功能分子膜的表面光谱和显微镜研究

• 批准号: RGPIN-2022-02954
• 负责人: Lipkowski, Jacek
• 金额: $ 2.62万
• 依托单位: University of Guelph
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=747978
• 关键词: Surface; spectroscopy; microscopy; studies; functional

The general objective of this research program is to study the structure and reactivity of phospholipid bilayers deposited onto a metal electrode at the metal-solution interface. The functionality of these films will be determined by the presence of peptides and proteins. We will build asymmetric bilayer that mimics outer membrane (OM) of a gram-negative bacterium and will investigate interactions of the large antibacterial peptides with lipopolysaccharides (LPS) that constitute the outer leaflet of the outer bacteria membrane. Our goal is to learn how the peptides bound to the LPS and how they cause a poration of the membrane. We will investigate how the electric field affects the stability of the asymmetric bilayers in which top leaflet consisting of LPS and the bottom leaflet of phospholipids and incorporation of antibiotics into such membrane. We will use Langmuir-Schaeffer technique to assemble the asymmetric bilayer. We will employ electrochemical impedance spectroscopy (EIS) to provide information about the membrane barrier properties for the transport of ions (resistivity). The scanning probe microscopies such as scanning tunneling microscopy (STM) and atomic force microscopy (AFM) will be used to provide molecular level images of the monolayer of lipopolysaccharides (LPS) and the asymmetric bilayer. In situ photon polarization modulation Fourier transform infrared reflection absorption spectroscopy (PM-IRRAS), surface enhanced infrared (SEIRAS) and surface enhanced Raman spectroscopy (SERS) will be used to investigate conformation, orientation, interactions, and penetration of the peptides with and through the bilayer. The spectroscopic techniques are complementary; PM-IRRAS will provide information about steady state properties of the bilayer with and without the peptides. SEIRAS will be used to investigate kinetics of the structural changes induced by antibiotic peptides and their insertion or transport across the bilayer. SERS has unique potential for studies of polysaccharides. Its spectral range is extended down to very low wavenumbers and its signal is not affected by the spectral interferences caused by the presence of water. We will employ several platforms to obtain high quality SERS spectra of polysaccharides such as shell isolated gold nanoparticles, array of pure gold nanoparticles and array of gold nanocavities. In another theme we will apply spectroscopic tools to investigate the mechanism of bonding of CO2 reducing enzymes such as formate dehydrogenase, (FDH) without and with metal centers to conductive supports and their performance to convert CO2 to useful chemicals.  Our task will be to apply spectroscopic methods to provide information about the nature of the bond formed with conductive support, and structural changes of the enzyme accompanying changes of the redox state of its redox center.

本研究计划的总体目标是研究沉积在金属-溶液界面上的金属电极上的磷脂双层的结构和反应性。这些膜的功能将由多肽和蛋白质的存在决定。我们将构建模拟革兰氏阴性细菌外膜（OM）的不对称双分子层，并将研究大抗菌肽与构成细菌外膜外叶的脂多糖（LPS）的相互作用。我们的目标是了解肽是如何与脂多糖结合的，以及它们是如何引起膜的穿孔的。我们将研究电场如何影响不对称双分子层的稳定性，其中上小叶由LPS组成，下小叶由磷脂组成，并将抗生素掺入这种膜。我们将使用Langmuir-Schaeffer技术来组装不对称双分子层。我们将采用电化学阻抗谱（EIS）来提供有关离子传输的膜屏障特性（电阻率）的信息。扫描探针显微镜，如扫描隧道显微镜（STM）和原子力显微镜（AFM）将被用来提供分子水平图像的单层脂多糖（LPS）和不对称双层。原位光子偏振调制傅立叶变换红外反射吸收光谱（PM-IRRAS）、表面增强红外光谱（SEIRAS）和表面增强拉曼光谱（SERS）将用于研究肽与双分子层的构象、取向、相互作用和渗透。光谱技术是互补的；PM-IRRAS将提供有和不含肽的双分子层稳态特性的信息。SEIRAS将用于研究抗生素肽及其在双分子层上的插入或运输引起的结构变化的动力学。SERS在多糖研究中具有独特的潜力。它的光谱范围被扩展到非常低的波数，其信号不受水的存在引起的光谱干扰的影响。我们将采用多个平台获得高质量的多糖SERS光谱，如壳分离金纳米粒子、纯金纳米粒子阵列和金纳米空腔阵列。在另一个主题中，我们将应用光谱工具来研究二氧化碳还原酶（如甲酸脱氢酶，FDH）在没有或有金属中心的情况下与导电支架的结合机制，以及它们将二氧化碳转化为有用化学物质的性能。我们的任务是应用光谱学方法来提供与导电载体形成的键的性质，以及伴随其氧化还原中心氧化还原状态变化的酶的结构变化的信息。