Exploring Dopamine Neurotransmitter and Silver Nanocluster (Ag _n ; <i>n</i> = 4–20) Interactions: DFT Insights for Biomedical Applications

This study investigates the interactions between silver nanoclusters (Ag_n; <i>n</i> = 4-20) and the dopamine neurotransmitter using density functional theory calculations. Our results demonstrate significant binding of silver nanoclusters to the amine group of the ethylamine side chain of dopamine. The adsorption energies range from -20 to -30 kcal/mol, suggesting favorable interactions. The results reveal strong binding specifically, supported by molecular electrostatic potential, quantum theory of atoms in molecules (QTAIM), and reduced density gradient analyses. The influence of water as a solvent on the interactions was also evaluated through the integral equation formalism-polarizable continuum model. The presence of water as a solvent slightly affects the stability and electronic features, notably increasing the dipole moments and solubility in polar environments. QTAIM analysis confirms the existence of dative Ag-N bonds with ionic character, characterized by low electron densities and positive Laplacians. Ab initio molecular dynamics simulations of select systems (DOP@Ag₅ and DOP@Ag₁₀) demonstrate their thermal and structural stability at 320 K, indicating their robustness under physiological conditions. Overall, this work offers insights into the adsorption mechanisms of dopamine on silver nanoclusters with potential implications for advancements in biosensing applications.