“A particle with a physicochemical structure on a scale greater than atomic/molecular dimensions but less than 100 nm, which exhibits physical, chemical and/or biological characteristics associated with its nanostructure. A nanostructured particle may be much larger than 100 nm. For example, agglomerates of TiO2 nanoparticles that are significantly larger than 100 nm in diameter may have a biological activity determined by their nanoscale substructure. Other examples include zeolites, meso-porous materials and multifunctional particulate probes.”¹

“It is conceivable that nanostructured particles of a few micrometers in diameter and below (such as fragments of a nano-composite or a nanostructured surface coating) may exhibit nanostructure-dependent biological properties.”²

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, §1.0. 2. 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, §4.0.