Determination of the structure of adenine monolayers adsorbed at Au(110)/electrolyte interfaces using reflection anisotropy spectroscopy

Abstract

Reflection anisotropy spectroscopy (RAS) has been used to show that at saturation coverage adenine adsorbs on the Au(110)/electrolyte interface in a base-stacking configuration with the plane of the bases orientated vertically on the surface and with the long axis of the molecules parallel to the [110] direction. Changes in the RAS observed from adsorbed adenine as a result of changes in the potential applied to the Au(110) electrode could arise from slight changes in the orientation of the molecules in the vertical plane.

The influence of pH on the structure of adenine monolayers adsorbed at Au(110)/electrolyte interfaces

“…The complexity of this process will be discussed in detail in a future publication [14]. The RAS profile observed from adenine adsorbed from a solution of pH 7.1 is, as expected, almost identical to those obtained in the earlier studies [3,4]. It is clear from Fig.…”

“…2(a). A larger variation in the RAS of the initial Au(110)/electrolyte interfaces was obtained in these three experiments than in other experiments in which the Au(110) surface was prepared using the flame annealing procedure [3,[7][8][9][10]. The origin of the spectral features of gold have been identified previously [6] and references therein.…”

“…2 that varying the pH of the solution has dramatic effects on the RAS of adenine adsorbed at the Au(110)/electrolyte interface. These effects are much stronger than the effects on the RAS of adsorbed adenine arising from variations in the concentration of the solution, the degree of surface coverage or the application of varying potentials to the Au(110) electrode [3,4]. In order to deduce further information about the orientation of the adsorbed adenine, it is necessary to consider the dipole transitions that are expected to contribute to the optical response of the molecules.…”

“…The structure and stability of model systems such as amino acids or nucleic acids on well understood metal surfaces provide insight into the understanding of more complex biological systems [1,2]. In a previous work [3] it was shown that at saturation coverage adenine adsorbs at the Au(110)/electrolyte interface in a base stacking configuration with the plane of the bases orientated vertically on the surface and with the long axis of the molecules parallel to the [110] direction. At subsaturation coverage the adenine molecules have been shown to adopt the same base stacking configuration as at saturation coverage and it is possible to determine the percentage of the Au(110) surface that is covered by adenine using reflection anisotropy spectroscopy (RAS) [4].…”

Evidence for protein conformational change at a Au(110)/protein interface

“…This might reflect conformational differences between wild-type and mutant proteins that affect the local environment around the FAD isoalloxazine ring [12]. As with the wild-type ETF, the ETF 1e /ETF 2e couple was ⪡ −250mV for the engineered ETF proteins and not accessible [9] using this method.RAS is a surface-sensitive optical technique that has been used to probe molecular assembly and changes in molecular orientation at metal/liquid interfaces [13][14][15][16][17]. The preparation of the Au(110) single crystal used to immobilize engineered variants of ETF together with a description of the electrochemical cell, potentiostat and RAS instrument [18] have been described previously [15].…”