Modeling of nanoparticle coatings for medical applications

Abstract: Gold nanoparticles (AuNPs) have been shown to possess properties beneficial for thetreatment of cancerous tumors by acting as radiosensitizers for both photon and ionradiation. Blood circulation time is usually increased by coating the AuNPs withpoly(ethylene glycol) (PEG) ligands. The effectiveness of the PEG coating, however,depends on both the ligand surface density and length of the PEG molecules, making itimportant to understand the structure of the coating. In this paper the thickness, ligandsurface density, and density of the PEG coating is studied with classical moleculardynamics using the software package MBN Explorer. AuNPs consisting of 135 atoms(approximately 1.4 nm diameter) in a water medium have been studied with the number of PEGligands varying between 32 and 60. We find that the thickness of the coating is onlyweakly dependent on the surface ligand density and that the degree of water penetration isincreased when there is a smaller number of attached ligands.