Multilayer Model of Gold Nanoparticles (AuNPs) and Its Application in the Classical Molecular Dynamics Simulation of Citrate-Capped AuNPs

Studies on the interaction between gold nanoparticles(AuNPs) andfunctional proteins have been useful in developing diagnostic andtherapeutic agents. Such studies require a realistic computationalmodel of AuNPs for successful molecular design works. This study offersa new multilayer model of AuNPs to address the inconsistency betweenits molecular mechanics' interpretation and AuNP's plasmonicnature. We performed partial charge quantum calculation of AuNPs usingAu(13) and Au-55 models. The result showed thatit has partial negative charges on the surface and partial positivecharges on the inner part, indicating that the AuNP model should becomposed of multiatom types. We tested the partial charge parametersof these gold (Au) atoms in classical molecular dynamics simulation(CMD) of AuNPs. The result showed that our parameters performed betterin simulating the adsorption of Na+ and dicarboxy acetonein terms of consistency with surface charge density than the zerocharges Au in the interface force field (IFF). We proposed that themultiple-charged AuNP model can be developed further into a simplerfour-atom type of Au in a larger AuNP size.