Table 1.

Overview of ENM classes and examples of properties which are associated with toxicity responses to the respective ENM class and the observed phenomenon or mode of action.

ENM class	ENM Property associated with toxicity	Toxicological Phenomenon obrserved/Mode of action
Metal	Shedding heavy metal (eg. Ag, Cu, Pt)	DNA cleavage and damage leading to genotoxicity and mutation; heavy metal ions induced oxidative stress and inflammatory responses
	Surface chemistries that affect the structure and function of proteins (e.g. Au)	Protein denaturation that may lead to inactivation of hormones or proteins, opening of cryptic epitopes that could lead to autoimmune diseases, protein fibrillation and accumulation of mis-folded protein could lead to disease conditions such as Alzheimers
Metal oxide	Dissolution and heavy metal release (e.g. ZnO)	Heavy metal ions induced oxidative stress and inflammatory responses
	Electron hole pair generation during photoactivation (e.g. TiO2)	Electron hole pair generation during photo-activation leading to free radical generation.
Silica particles	Surface defects (e.g. SiO2)	Blood platelet, vascular endothelial and clotting abnormalities
Metal chalgenide	Heavy metal release (e.g. CdSe Qantumdots)	ROS generation, lipid peroxidation, DNA damage
Fullerenes and CNTs	Heavy metal contaminantion, Aspect ratio >5	Fibrogenesis and tissue remodeling injury, oxygen radical production, GSH depletion, bio-catalytic mechanisms
Polymer	Cationic charge density	Membrane damage/leakage/thinning Protein binding or unfolding responses/, denaturation of proteins or fibrillation, lysosomal damage through proton pump inactivation or lysis of lysosomes