How To Study If Nanoparticles Are Toxic? (I)
The suitability of different cellular in vitro immunotoxicity and genotoxicity methods for the analysis of nanoparticle-induced events.
Studies of toxicity have been developing strategies and protocols for decades to assess the safeness of chemical compounds. When reaching the nanoscale, inorganic materials may be viewed as macromolecules and then the study of their toxicity to follow similar protocols. However, the physico-chemical signatures of NPs make such adaptation, from molecules to nanoparticles, not so trivial in some cases. Thus, suitable assays and test strategies are needed to analyze potential noxious health effects caused by nanoparticle exposure. The development and validation of such methods is challenging because nanoparticles may show unexpected behavior, like aggregation or interference with optical measurements, when routine in vitro assays are performed.
In this interdisciplinary study, the effects of inorganic gold (4.5 nm) and iron oxide (7.3 nm) nanoparticles with a narrow size distribution were tested on human cells using different assay systems. The results show that cytotoxicity as well as immunotoxicity and genotoxicity induced by these two inorganic nanoparticles was low or absent when using a panel of cell-based tests in different laboratories. However, several technical issues had to be tackled that were specific for working with nanoparticles. The methods used, their suitability for nanotoxicity testing, and the technical problems encountered are carefully described and discussed in this paper.