Electrochemical UV-SERS of adenine on cobalt electrode

The combination of surface-enhanced Raman spectroscopy in the ultraviolet spectral region (UV-SERS) with resonance Raman scattering enhancement, referred to as UV-SERRS, enables ultrasensitive and reliable detection of biomolecules because of the strong electronic transition of many biologically important compounds in UV region. Adenine solution studies by UV-Raman spectroscopy revealed pre-resonant enhancement of various modes by 2-16 times at 325 nm excitation wavelength. Adsorption and structural properties of adenine on a cobalt electrode were probed by UV-SERS. The nanostructured cobalt electrode was prepared via electrodeposition from diluted aqueous CoSO₄ solutions under negative electrode potentials. Using 325 nm excitation, potential-dependent UV-SERS spectra of adenine adsorbed on the Co electrode were obtained. Based on analysis of isotopic H₂O/D₂O substitution, concentration- and potential-dependent spectra, the bonding and structure of adsorbed molecule were revealed. Adenine primarily adsorbs in its N9H form, interacting with cobalt through the N7 atom of the imidazole ring and the amino group, with its ring plane nearly perpendicular to the surface. These findings highlight adenine's potential as a model for studying nucleobase-metal interactions, which is crucial for applications in biosensing, molecular electronics, and surface passivation. The study underscores cobalt's viability as a cost-effective, stable and magneto-plasmonic UV-SERS substrate, opening new avenues for the development of advanced analytical techniques.