Single molecule and single particle spectroelectrochemistry

光学方法的最新进展已经允许用于单分子检测的光谱技术的发展。这些技术已被广泛用于揭示重要的机制方面，主要是从生物系统。例如，它们可以提供有关结合过程中蛋白质构象变化的信息，或有关单个物质跨细胞膜转运的信息。电化学过程是几种技术的核心，包括能量产生和储存（燃料电池和电池）。然后可以探索提供电化学条件下表面过程的分子图像的分析方法，以改进这些技术。然而，单分子技术很少被应用于研究电化学过程。在过去的几年里，我们的研究小组一直致力于开发金属纳米结构作为研究单分子表面过程的方便平台。这些纳米结构中的电势可以被控制，并且可以通过系统的电化学和光谱响应（光谱电化学）同时研究表面化学反应。金属系统的纳米尺寸允许限制单个分子进行研究。这项发现补助金的目标是利用这些进展开发新的混合化学方法，重点是它们在单分子研究中的应用。该计划的一个方面将涉及单分子表面增强拉曼散射（SM-SERS）从带电接口，一项技术由我们的小组开创。Sers热点的性质和量化的基础研究将与表面浓度的电化学测定相结合。这种类型的信息将提供基础的动力学和热力学吸附性能的测定在SM水平。近场技术，如近场扫描光学显微镜（NSOM）和尖端增强拉曼散射（TERS），也将被实施来研究固定在碳载体上的单个纳米颗粒燃料电池催化剂（Au，Au-Pt和Au-Pd纳米颗粒）的电化学性质。来自各种簇的单个性质将导致更好地理解它们对催化剂的平均性质的影响。SM光谱电化学的第二种方法将涉及在金薄膜中作为纳米电极的周期性纳米孔阵列（PANH）的应用。只有孔内的体积将是电化学可访问的，因此，每个单独的孔将作为纳电化学实验的阿升小瓶。PANH电极将被用于研究单分子蛋白质的电化学动力学，成为单分子电化学研究的新平台。这里提出的研究，然后将提供基本的见解分子方面的技术意义的领域的电催化，特别是燃料电池。这些项目还将最终在单分子审讯设备，将被翻译为生物医学应用的分析一个单一的活细胞和神经化学。

Recent advances in optical methods have allowed the development of spectroscopic techniques for single molecule detection. These techniques have been widely used to unveil important mechanistic aspects, mainly from biological systems. For instance, they can provide information about the changes in protein conformation during binding or regarding the transport of individual species across cell membranes. Electrochemical processes are central to several technologies, including energy generation and storage (fuel cell and batteries). Analytical methods that provide a molecular picture of surface processes in electrochemical conditions could then be explored to improve those technologies. However, single molecules techniques have seldom been applied to study electrochemical processes. In the last few years, our research group has been engaged in the development of metallic nanostructures as convenient platforms to investigate single molecular surface processes. The electric potential in those nanostructures can be controlled and surface chemical reactions can be investigated simultaneously by the electrochemical and spectroscopic response of the system (spectroelectrochemistry). The nanometric dimensions of the metallic system allow the confinement of individual molecules for investigation. The goal of this discovery grant will be to use these advances to develop new hybrid chemical methods, with emphasis on their application in single molecule studies. One aspect of the program will be related to single molecule surface-enhanced Raman scattering (SM-SERS) from electrified interfaces, a technique pioneered by our group. Fundamental investigation of the nature and on the quantification of SERS hotspots will be carried out in combination with electrochemical determination of surface concentrations. This type of information will provide the basis for the determination of kinetics and thermodynamic adsorption properties at the SM level. Near field techniques, such as near-field scanning optical microscopy (NSOM) and tip-enhanced Raman scattering (TERS), will also be implemented to investigate electrochemical properties from single nanoparticle fuel cell catalyst (Au, Au-Pt and Au-Pd nanoparticles) immobilized in carbon supports. Individual properties from a variety of clusters will lead to a better understanding of their effect on the average property of the catalyst. A second approach to SM spectroelectrochemistry will involve the application of periodic array of nanoholes (PANH) in gold thin films as nanoelectrodes. Only the volume inside the holes will be electrochemically accessible, so, each individual hole will work as attoliter vials for nanoelectrochemistry experiments. The PANH electrodes will be used to study the electrochemistry dynamics of of single proteins and will became a new platform for single molecule electrochemistry studies.*The research proposed here will then provide fundamental insights into molecular aspects of technological significance to the field of electrocatalysis, particularly for fuel cells. These projects will also culminate in devices for single molecule interrogation that will be translated to biomedical applications for the analysis of a single living cell and in neurochemistry.