The Application Of Surface-enhanced Infrared Absorption Spectroscopy (SEIRAS) In The Study Of Interfacial Redox Protein Electron Transfer Mechanism

In recent years, surface-enhanced infrared absorption spectroscopy (SEIRAS) hascontributed significantly to the deeper and directly studies about proteins’ structures andfunction from the molecule level, and it is because of its simple surface selection rules andhigh sensitivity. SEIRAS and electrochemistry have been combined and used for in situFT-IR transformation detection which leading by electrochemistry changes. It is the mostlyextensity measure to investigate the oxidation-reduction proteins’ electron transfer mechanism.However, the application of SEIRAS in membrane protein was limited by its enhancementfactor (101~103).Therefore, the enhancement factor should be advanced. This dissertationmainly consists of the following three aspects:1. We explored the adsorption of horse heart cytochrome c (Cyt c) on bare Au electrodeby surface-enhanced infrared absorption (SEIRA) spectroscopy on the molecular level. Ourresults revealed that the native secondary structure of adsorbed Cyt c has been kept even onbare Au surface. The hampered electron transfer was mainly caused by its adsorptionorientation.2. We have monitored the effect of adsorbed gold nanoparticles on the redox-inducedsurface-enhanced infrared difference absorption spectrum (SEIDAS) of cytochrome c inAu-Cyt c-AuNPs sandwich architecture by SEIRA spectroscopy. Our results indicated that theSEIRA difference spectrum of the vibration of the heme was significantly increased in theintensity due to the adsorption of gold nanoparticles on the Cyt c. This was induced by theelectron transfer between the heme and the gold nanoparticles, which also promoted electrontransfer of adsorbed protein. Our study provides a new method for optimal theelectrochemical protperty of adsorbed protein.3. We constructed a metal–molecule–metal sandwich nanostructure. Our results indicatedthat the adsorption of gold nanorods increases the spectra intension of adsorbed probemolecule, the additional enhancement factor is~6on the basis of the SEIRAS. Theenhancement mechanism of the sandwich nanostructure may due to the electromagneticmechanism and chemical mechanism.