Effect of the Ligand Binding Strength on the Morphology of Functionalized Gold Nanoparticles

Abstract

Functionalized gold nanoparticles are investigated by density functional theory calculations in the context of cancer radiotherapy. Several typical experimental shapes including nanostar, nanosphere and nanorod are modeled by optimizing Au clusters covered by organic monolayers composed of hydrated short-chain polyethylene glycol (PEG) ligands. The PEGylation stabilizes significantly the stellation of decahedral Au54 by deforming significantly its geometry at the spikes. The higher stability of the PEG molecules adsorbed on this stellated nanocluster with respect to the more spherical icosahedral Au55 and Au79 leads to a larger energy cost to desorb them and thus a weaker propensity for the starred nanoparticle to exchange ligands with the cell membrane, in agreement with experiments. These results open interesting perspectives for advancing on the understanding of the cellular uptake of gold nanoparticles.