Toxicity assessment of engineered nanomaterials: resolving the challenges.

The concern over the adverse effects of nanomaterials on humans has lead to an extensive research on the fate of nanoparticles in biological systems. However, unique properties of engineered nanomaterials yield many technical challenges which impede nanotoxicity studies. Some of these challenges are: interference of nanoparticles with in vitro toxicity assays, dissolution, studying cellular uptake and visualization, proper characterization, agglomeration etc. In the present study, zinc oxide (ZnO) nanoparticles were characterized for their size by dynamic light scattering which revealed their monodisperse nature. The cellular uptake of ZnO nanoparticles was analysed by flow cytometry. A significant increase in the percentage intensity of side scattering of cells treated with nanoparticles was observed as compared to the granularity of control cells. Further, the role of dissolution was evaluated by exposing cells to ZnCl2 at an equimolar dose of released zinc. No decrease in the cell viability was observed suggesting minimal role of dissolution in ZnO nanoparticle induced toxicity.