Surface-Enhanced Raman Evidence of Protonation, Reorientation

Jun 20, 2011 - Quantitative surface-enhanced Raman spectroscopy of single bases in oligodeoxynucleotides. S. Dick , S. E. J. Bell. Faraday Discussions...
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Surface-Enhanced Raman Evidence of Protonation, Reorientation, and Ag+ Complexation of Deoxyadenosine and Deoxyadenosine-50-Monophosphate (dAMP) on Ag and Au Surfaces Evanthia Papadopoulou and Steven E. J. Bell* Innovative Molecular Materials Group, School of Chemistry & Chemical Engineering, Queen’s University, Belfast BT9 5AG, U.K.

bS Supporting Information ABSTRACT: Surface-enhanced Raman (SERS) spectra of deoxyadenosine and 50 -dAMP on Ag and Au surfaces showed the protonation of both compounds in the N1 position, their orientation geometry on metal surfaces, and the formation of Ag+ complexes at alkaline pH on hydroxylamine-reduced Ag colloids. Interestingly, substitution at the N9 position caused dramatic changes in the relative band intensities within the spectra of both deoxyadenosine and 50 -dAMP compared to that of simple adenine, although they continued to be dominated by adenine vibrations. Concentration-dependent spectra of 50 -dAMP were observed, which matched that of adenine at high concentrations and that of deoxyadenosine at lower concentration (