Electrochemical In-situ SERRS Spectroscopic Study Of Azurin Adsorbed On Self-assembled Monolayers Modified Gold Electrodes

As a representative of the blue copper proteins, azurin has excellent redox activity and reversible electron transfer characteristic in organism. Previous investigations mainly focused on its electron transfer characteristic by using traditional electrochemical techniques. However, the information obtained from these traditional electrochemical techniques is the sum of various kinds of information, and it only deals with this redox protein at macroscopic and empirical level, not at molecular level. As a result, it cannot provide us with some essential and critical information about the molecular structure and electronic configuration of intermediates and transition states involved in the electron transfer processes of azurin. Accordingly, the analysis from these investigations is not convincing enough to interpret the mechanism of this process. Due to of the molecular structure features of redox proteins such as azurin, it is possible for us to utilize resonance Raman spectroscopy to characterize their molecular structures. Therefore, electrochemical in situ SERS spectroscopic technique was employed here to investigate the redox process of azurin.The thesis presented here consists of three parts: (1) By normal Raman and SERS spectroscopic as well as theoretical calculation analysis, with change of the electrode potential or the solution pH value, the variations of molecular conformation and orientation of glycine, as one of active-site amino acids in azurin, adsorbed on roughened silver electrode surface were characterized and analyzed. This part established the foundation for the electrochemical in-situ SERS spectroscopic study of azurin; (2) The structure and performance of some mixed SAMs , which are comprised of different proportion and chain length of alkylthiol and 12-mercaptododecanoic acid, were investigated by electrochemical,XPS and AFM techniques for the purpose of their applications in azurin biochemistry. (3) Based upon the research work mentioned above, the electron transfer process of azurin adsorbed on the appropriate single-component or the mixed SAMs were characterized by electrochemical in situ SERRS technique. Then some important information about the molecular conformation and interaction between adsorbate and the SAMs were further obtained from these SERRS spectra.