Chemical impact.

The chemical nature of nanomaterials and the presence of absorbed elements at the surface (PAH, transition metals,…) are likely to influence the toxicity. When the nanoparticles have undergone a surface treatment, the toxicity may also depend on the nature of the coating. 

Many nanoparticles have the ability to develop reactive species of oxygen which have an essential role in the process of inflammation. If anti-oxidant mechanisms of the organism don’t have sufficient capacity to inactivate them, the species will alter the biological surrounding tissues.