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DFT and SERS Study of 15N Full-Labeled Adenine Adsorption on Silver and Gold Surfaces

Yao, Guohua, Zhai, Zhimin, Zhong, Jie, Huang, Qing
The Journal of Physical Chemistry C 2017 v.121 no.18 pp. 9869-9878
Raman spectroscopy, adenine, adsorption, gold, nanogold, nanoparticles, nitrogen, nucleic acids, silver, stable isotopes
Adsorption of nucleic acid bases on metal surface of nanoparticles has received much attention recently in bio- and nanotechnology, while it still remains a controversial problem in how adenine is adsorbed onto the metal surface. As the nitrogen in adenine plays an important role in the molecular recognition and interaction, the spectral feature related to the nitrogen is the key to analysis of the adsorption configurations. For this purpose, we employed density functional theory (DFT) calculations at B3LYP/6-311+G(d,p) level for the simulation of adsorption configurations, and in the meantime we checked the corresponding surface enhanced Raman spectroscopy (SERS) of ¹⁵N fully labeled adenine adsorbed on the surfaces of silver and gold nanoparticles both experimentally and theoretically. The agreement of spectral positions, intensities, and isotopic shifts of the SERS bands, suggests that adenine adsorbed on either silver or gold surface takes the same adsorption configuration in which N7H adenine interacts with Ag₄⁺/Au₄⁺ cluster through both N3 and N9 sites. This study therefore may not only provide new insight into the interaction of adenine with noble metals but also have demonstrated the effective approach based on the combination of DFT and SERS tools applied in isotopic molecules to the issue of adsorption of nucleic acid bases onto metal surfaces in general.