DNA/RNA nucleobases sensing by silicon nanowires: A DFT study

Abstract

This study employs density functional theory (DFT) to explore the interaction between hydrogenated silicon nanowires (SiNW) and DNA/RNA nucleobases (adenine, cytosine, guanine, thymine, and uracil). We investigate various adsorption configurations (both perpendicular and parallel to the nanowire surface) to elucidate the adsorption energies, recovery times, charge transfers, and the consequent modifications in the electronic properties of the SiNW. Our findings reveal that, in most cases, the nucleobases chemisorb onto the SiNW surface with adsorption energies exceeding 0.5 eV, except for specific thymine configurations exhibiting lower binding. Notably, cytosine displays the highest adsorption energy, resulting in exceptionally long recovery times and significant charge redistribution indicative of strong covalent-like interactions. In contrast, adenine, guanine, and uracil exhibit lower adsorption energies and rapid desorption dynamics, suggesting their suitability for reusable sensor applications. Furthermore, the adsorption process induces considerable changes in the SiNW band structure, such as the formation of mid-gap states and shifts in the work function, thereby modulating the nanowire's electrical conductivity and optical properties. These results underscore the potential of SiNW as highly selective, label-free platforms for nucleobase detection and advanced DNA/RNA sequencing devices.