DNA bases assembled on the Au(110)/electrolyte interface: a combined experimental and theoretical study

Area of Science:

• Surface Science
• Electrochemistry
• Computational Chemistry

Background:

• The Au(110) surface is highly active for molecular adsorption but lacks detailed electrochemical data.
• Understanding nucleobase adsorption on gold is crucial for biosensor development and nanotechnology.

Purpose of the Study:

• To investigate the adsorption behavior of adenine (A), cytosine (C), guanine (G), and thymine (T) on the Au(110) electrode surface.
• To elucidate the molecular packing, adsorption energies, and interactions of these DNA bases on Au(110).

Main Methods:

• Cyclic Voltammetry (CV) to study electrochemical adsorption.
• Electrochemically controlled Scanning Tunneling Microscopy (EC-STM) to visualize adlayer structures.
• Density Functional Theory (DFT) calculations to determine adsorption energies and geometries.

Main Results:

• DNA base adsorption on Au(110) leads to featureless voltammograms and reduced double-layer capacitance, indicating chemisorption.
• EC-STM reveals lifting of the Au(110) reconstruction, specific molecular packing, and pH-dependent adsorption for adenine and guanine.
• DFT calculations provide insights into adsorption energies, preferred orientations, and the physical nature of adsorbate-surface interactions.

Conclusions:

• The study proposes specific adsorption orientations and interaction mechanisms for A, C, G, and T on Au(110).
• Significant differences in adsorption behavior are observed compared to Au(111) and Au(100) surfaces.
• Combined experimental and theoretical approaches offer a comprehensive understanding of nucleobase adsorption on low-index gold surfaces.