Evidences of adenine-thymine Interactions at gold electrodes interfaces as provided by in-situ infrared spectroscopy

The co-adsorption of complementary DNA bases adenine and thymine on gold thin-film electrodes from 0.1 M HClO4 solutions in H2O and D2O is studied by surface-enhanced infrared absorption spectroscopy in the attenuated total reflection mode (ATR-SEIRAS). The comparison of the spectra in the range 1750-1550 cm(-1) for co-adsorbed adenine and thymine at controlled potentials to those of the individual adsorbed bases shows the enhancement of the signals associated to the vibration modes of adenine and the inhibition of those of thymine. The results can be explained by invoicing the rearrangement of both molecules on the electrode surface in order to facilitate the Watson-Crick (W-C) and/or Hoogsteen (HG) interactions between the bases. The co-adsorption seems to be a cooperative process in which a low surface concentration of each base can induce the rearrangement of the complementary base molecules on the surface. (C) 2013 Elsevier B.V. All rights reserved.