Fig. 2

Illustration of mechanisms of radiation damage in the presence of nanoparticles. In addition to the direct and indirect damage (yellow and red stars, respectively) to DNA or other parts of the cell (a), the incident radiation may also interact with NPs (b) (illustrated by dashed, wiggly arrows) and induce the emission of secondary electrons which can then react with the medium to increase the production of radicals and other reactive species (like \({\cdot }\)OH radicals); secondary electrons produced by the radiation or by NPs may also induce further electron emission from NPs. c All the secondary species may diffuse and damage other parts of the cell (like mitochondria). See text for further details