Folic acid adsorption on pristine and oxygen-terminated boron nitride and silicon carbide nanoparticles: A DFT and MD simulation study

Abstract

This study investigates the adsorption of folic acid (FA) onto pristine and oxygen-terminated boron nitride (BN) and silicon carbide (SiC) nanoparticles using density functional theory (DFT) and molecular dynamics (MD) simulations. Employing the Perdew-Burke-Ernzerhof functional with the D3 dispersion correction (PBED3) within a water solvent environment, we determined that FA adsorption is energetically favorable on both nitrogen-terminated BN (−0.92 eV) and oxygen-terminated SiC (−0.99 eV). This binding is driven by electrostatic interactions between the -NH and -OH groups of FA and the nitrogen and carbon atoms of the nanoparticles. Oxygen termination marginally enhanced the binding energy in both nanoparticle types. Thermodynamic analysis confirmed the adsorption process to be exothermic and spontaneous. MD simulations further revealed a hierarchy in FA interaction strength with BN nanoparticles: O > N > B, with O-terminated BN exhibiting the strongest interaction. This stronger interaction correlated with reduced FA mobility, indicating tight binding. Conversely, weaker interactions, particularly with boron-terminated BN, resulted in increased FA diffusion and higher mean square displacement (MSD). The adsorption of FA significantly altered the electronic and optical properties of both BN and SiC nanoparticles, with a termination-dependent effect. Specifically, FA adsorption substantially reduced the HOMO-LUMO gap, most notably in boron-terminated BN (76.83 % reduction) compared to oxygen-terminated SiC (72.94 % reduction), leading to increased conductivity. This enhanced conductivity, coupled with the low recovery times and improved dipole moments observed, suggests the potential utility of BN and SiC nanoparticles as biosensors for FA detection. The promising adsorption energies also highlight their potential application in drug delivery systems.