Abstract
In this study, the interaction between the neurotransmitter epinephrine and small gold nanoclusters (Au(n)NCs) with n = 6, 8, and 10 is described by density functional theory calculations. The interaction of Au(6), Au(8), and Au(10) nanoclusters with epinephrine is governed by Au-X (X = N and O) anchoring bonding and Au···H-X conventional hydrogen bonding. The interaction mechanism of epinephrine with gold nanoclusters is investigated in terms of electronic energy and geometrical properties. The adsorption energy values for the most favorable configurations of Au(6)NC@epinephrine, Au(8)NC@epinephrine, and Au(10)NC@epinephrine were calculated to be -17.45, -17.86, and -16.07 kcal/mol, respectively, in the gas phase. The results indicate a significant interaction of epinephrine with Au(n)NCs and point to the application of the biomolecular complex Au(n)NC@epinephrine in the fields of biosensing, drug delivery, bioimaging, and other applications. In addition, some important electronic properties, namely, the energy gap between HOMO and LUMO, the Fermi level, and the work function, were computed. The effect of aqueous media on adsorption energy and electronic parameters for the most favorable configurations was also studied to explore the influence of physical biological conditions.