When nanomaterials are exposed to complex systems such as food, they may cause major changes in physical and chemical properties and even toxicity. Toxicity evaluation of complex systems is imminent. Unfortunately, to date, no database has been established on the toxicity changes of nanoparticles in composite systems. The change of ZnO nanoparticles (ZnO NPs) in the composite system and its toxicity mechanism were studied. The results show that under certain conditions, the presence of zinc ions (Zn²⁺) in the acid system (vitamin C, tartaric acid or citric acid) with solubility of 100% can increase the toxicity of ZnO NPs. In the system of phosphoric acid, phosphate and glutathione, the complexation of ZnO NPs with Zn²⁺reduces the toxicity. The effect of nano-sized TiO₂NPs on ZnO NPs toxicity depends on the size and surface properties of nano-sized TiO₂. In conclusion, the homeostasis level of intracellular Zn²⁺is a decisive factor in determining the toxicity of complex systems. The results showed that the toxicity of the composite system varied greatly, and there may be potential food safety problems, especially for unstable nanoparticles.

https://onlinelibrary.wiley.com/doi/full/10.1002/ppsc.201900214