Are gold nanoparticles so inert under ionizing radiation?

Abstract Coupling ionizing radiation with metallic nanoparticles enables several applications from catalysis to medicine. Development of nanoparticles for therapy requires initial biocompatibility assessment but also the absence of structural or chemical changes during or after treatment that could be responsible for new toxicity. In that context, we exposed gold nanoparticles to gamma irradiation in water solution and followed their surface plasmon resonance as a function of the dose. The initial diagnostic method, sensitive to nanoparticle size, morphology, or environment, revealed alterations in the gold nanospheres upon irradiation. Hydroxyl radicals were found responsible for oxidation of Au atoms that could then be released into solution or redeposit on the surface. Functionalization with PEG ligands was shown to be an effective protection of the nanoparticle surface.