Analyzing the Electrochemical Interaction of the Angiogenesis Inhibitor Batimastat by Surface-Enhanced Raman Spectroscopy

Abstract

This is the first work to describe the vibrational properties of the anticancer drug batimastat (BB-94) as an inhibitor of extracellular matrix metalloproteinase with a broad spectrum of activity. In addition, the adsorption of this molecule onto a silver roughened electrode surface using surface-enhanced Raman spectroscopy (SERS) was studied. This research provides a complete account of the influence of applied electrode potential and excitation wavelengths at the molecule-metal interface. Although vibrational assignment becomes more difficult as the molecule size increases, we performed density functional theory (DFT) at the B3LYP/6-31G(d,p) level of theory to calculate molecular geometry in the equilibrium state and Raman frequencies to clarify the nature of vibrational modes. The greatest amplification of the SERS signal occurs for the electrode potential of −0.3 V for the 532 nm excitation line and shifts as moves to the near-infrared laser line at 785 nm. The conclusion is that the mercaptothiophene part and one of the amide groups interact with the metal surface. This results in a charge transfer resonant process in the SERS of this molecule, which has been found by analyzing the charge transfer SERS profiles. Finally, there is the possibility of the formation of different adsorption species or metal complexes on the surface that could contribute to the whole signal observed in the SERS spectra.

Keywords

• surface-enhanced Raman spectroscopy (SERS)
• DFT calculations
• silver electrode
• electrode potential dependence
• excitation-wavelength dependence
• batimastat (BB-94)