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 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 potential mitigation and toxicity. While 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 viscera and liver, provides new insights into the mechanisms underlying its benefits at the individual level, informing strategies to minimize risks while maximizing benefits.