Variation in gold monolayer properties on interaction with DNA/RNA nucleobases useful for DNA sensing

Interfacing DNA/RNA nucleobases with gold nanoparticles (AuNPs) has been thoroughly investigated for several biomedical and diagnostic applications because of its numerous advantages. In this work, the interaction of DNA/RNA nucleobases with recently reported pristine gold monolayer in HCP structure, has been explored by utilizing the Ab-initio calculations. The binding characteristics between the two entities, the charge transfer, and the optical and electronic properties of the nucleobase-gold monolayer system, show distinct results for each nucleobase. The binding energies of the nucleobase-Au monolayer system vary as: G > A -C > T -U. The density of states of the nucleobase-gold monolayer system clearly reveals the modulation in electronic properties owing its origin to the presence of nucleobase atoms. The changes in optical properties (plasmon frequencies, reflection cofficient and refractive index), and tunneling current characteristic of gold monolayer are observed due to gold-nucleobase interactions. On adsorption of nucleobase on gold monolayer, additional peaks appear in the EELS spectra and imaginary part of dielectric function and the values of refractive index, static dielectric constant and reflectance increase. We observe higher tunnel current and enhanced negative resistance region for nucleobase adsorbed systems. The results indicate that pristine Au-monolayer in HCP structure is a good candidate for DNA/RNA sequencing devices. Results from our current study are helpful in understanding experimental findings and may be beneficial for advancements in biosensing technology.