Two-sided cellular and physiological effects of zinc oxide nanoparticles (nZnO): a critical review

Advances and applications of nanotechnology inevitably lead to the release of nanoparticles (NPs) into the environment, particularly zinc oxide nanoparticles (nZnO). This review focuses on the toxic and nutritional effects of nZnO at both the cellular and physiological levels as well as the corresponding molecular mechanisms involved. Understanding the cellular transport and dissolution characteristics of nZnO is essential to elucidate its potential toxicity mechanisms. Excess nZnO is absorbed into tissues and accumulates in cells, ultimately resulting in physiological inhibition, nutritional imbalances, and oxidative stress. Conversely, an appropriate amount of nZnO may enhance homeostasis at the organ level, induce moderate production of reactive oxygen species (ROS), and activate changes in antioxidant genes and KEGG pathways, thereby improving the anti-stress capacity of organisms. We also examine the fate of nZnO in marine fishes at the physiological and molecular levels. The effects of nZnO exposure are complex, exhibiting both benefits and toxicity. While the excessive use of nZnO poses ecological risks, a judiciously designed application of nZnO holds promise for various fields, including marine fish farming. The regulatory role of nZnO in fish organs, such as the viscera and liver, provides new insights into the mechanisms underlying nZnO benefits at the individual level, promoting strategies to minimize its risks while maximizing its benefits. © 2024 The Royal Society of Chemistry.