“A particle engineered or manufactured by humans on the nanoscale with specific physicochemical composition and structure to exploit properties and functions associated with its dimensions. Engineered nanoparticles include particles with a homogeneous composition and structure, compositionally and structurally heterogeneous particles (for instance, particles with core-shell structures) and multi-functional nanoparticles (for instance, ‘smart’ nanoparticles being developed for medical diagnostics and treatment).”¹

1. G. Oberdörster, A. Maynard, K. Donaldson, et al, “Principles for characterizing the potential human health effects from exposure to nanomaterials: elements of a screening strategy,” Particle and Fibre Toxicology 2005, 2:8.