[SERS spectra of L-carnosine under the interaction of coordination with adsorbed SnCl2]

The authors have found that by virtue of utilizing the interaction of strongly chemically adsorbed SnCl2 with the analytes of organic/biologic molecules, the authors can not only effectively eliminate the laser carbonization and oxidation of probe molecules (e. g. pyridine), but also obtain specially enhanced Raman signals (e. g. vitamin B6). This method is applicable to the SERS spectroscopic analysis of highly reactive organic/biologic molecules. In the present paper, the authors report the investigation results on the electrochemical SERS spectra of L-carnosine (LCar) for the first time, mainly concentrating on the influence of adsorbed SnCl2 and applied potential on the SERS spectra of LCar. The SERS spectra of LCar were badly interfered by laser carbonization in the absence of SnCl2. However, in the presence of SnCl2 high quality SERS spectra of LCar could be obtained free of carbonization. It is demonstrated that LCar can be immobilized on the gold substrate indirectly via surface coordination with the pre-adsorbed SnCl2 under potential control. Apparently, such a sandwich-like adsorption configuration as Au-Sn(II)-LCar is beneficial both to sensing the strong electromagnetic field at the nanostructured gold surface and to preventing the LCar from damage by the laser.