Ab-initio simulation of the interaction of gold nanoclusters with glycine

Abstract

Nanomaterial-Biomolecules complexes have several important applications in biological processes and bionanoscience. In this regard, the adsorption of the simplest amino acid (glycine) on the gold nanocluster has been studied to understand the interaction of amino acid with Au nanocluster. Small nanoclusters (neutral and cationic) of five, eight, thirteen, fifteen, and eighteen atoms have been utilized for this study. UV-Vis spectroscopy, Reduced Density Gradient (RDG), HOMO-LUMO analysis has been performed for nanoclusters and their glycine adsorbed complexes which provides information about the charge transfer binding mechanism, and establish the nature of interaction in glycine-gold nanocluster complexes. It is observed that the neutral and cationic Au nanoclusters show the highest adsorption energy for clusters of five, thirteen, and fifteen atoms. When the HOMO-LUMO energy gap of the cationic form of Au nanoclusters and glycine adsorbed Au nanoclusters are studied, it is observed that the HOMO-LUMO energy gap is decreased monotonically as cluster size increases in all cases (namely the lowest energy structure, first higher energy structure, and second higher energy structure). The results from the current work will be applicable as nanocluster sensors for glycine detection.