Analytical Sciences

Abstract − Analytical Sciences, 26(2), 135 (2010).

SERS Measurements of Magnetic Stretching Force-Induced Trans-Gauche Conformational Change
Takeyoshi GOTO and Hitoshi WATARAI
Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
The effects of stretching forces on covalently bridged 3-mercaptopropanoic acid molecules between magnetic particles (MPs) and Ag nano-particles (NPs) were studied by surface-enhanced Raman scattering (SERS) spectroscopy. With an exertion of 100 pN per single MP, the intensity ratio of the C-S stretching vibrations for trans-to-gauche conformations was increased from 0.295 ± 0.008 to 0.69 ± 0.09. From the experimental result, it was concluded that the magnetic forces increased the distance between the MP and the Ag NP surface, and induced a shift of the isomerization equilibrium to the trans conformation. The present approach is a new candidate for a dynamic force spectroscopy of conformational equilibria.