Influence of the Co-Adsorbed Ions on the Surface-Enhanced Raman Scattering Spectra of Dopamine Adsorbed on Nanostructured Silver

Abstract

The abnormal metabolism or imbalance of dopamine may lead to some neurological disorders. Therefore, the facile and fast detection of this neurotransmitter is essential in the early diagnosis of some diseases. One of the methods that can be used for the detection and determination of dopamine is the surface-enhanced Raman scattering (SERS). In this contribution, we report a very strong influence of some salts (we used salts containing Na+ cations and the following anions: SO42−, F−, Cl−, Br−, and I−) on the spectral patterns and intensity of the SERS spectra of dopamine adsorbed on a nanostructured macroscopic silver substrate. The analysis of the recorded SERS spectra based on the assignments of Raman bands from the density-functional theory (DFT) calculations and based on the SERS surface selection rules reveals that when molecules of dopamine are adsorbed from an aqueous solution to which no electrolytes have been added, they adopt a flat orientation versus the silver surface; whereas, the molecules of dopamine co-adsorbed with various ions interact with the silver surface, mainly via phenolic groups, and they adopt a perpendicular orientation versus the metal surface. An addition of electrolytes also significantly influences the intensity of the recorded SERS spectrum; for example, an addition of Na2SO4 to a final concentration of 1 M induces an increase in the intensity of the measured SERS spectrum by a factor of ca. 40. This means that the addition of electrolytes to the analyzed solution can reduce the limit of detection of dopamine by SERS spectroscopy. The abovementioned findings may facilitate the construction of dopamine SERS sensors.

SERS detection of dopamine using metal-chelated Ag nanoshell

“…This band was assigned to the aliphatic chain CH 2 -CH 2 bending. [48][49][50] Further, the detection of other molecules with hydroxyl group was demonstrated by utilizing AgNS@PVA@Cu. The SERS signals of catechol, naphthalene and serotonin were measured aer being mixed with AgNS@PVA@Cu (Fig.…”

Surface-Assisted Selective Air Oxidation of Phosphines Adsorbed on Activated Carbon

“…Adsorption of molecules on surfaces is a crucially important process with wide-ranging applications in academia and industry. Therefore, new developments in the separation sciences, as well as physical and analytical chemistry, appear frequently in the chemical literature. − Volatile adsorbates can be removed in vacuo, while washing with favorable solvents removes nonvolatile adsorbates.…”