Direct Interaction of Zirconia Nanoparticles with Human Immune Cells

Nanomaterials play a crucial role in various aspects of modern life. Zirconia nanoparticles, extensively employed in medicine for fortifying and stabilizing implants in reconstructive medicine, exhibit unique electrical, thermal, catalytic, sensory, optical, and mechanical properties. While these nanoparticles have shown antibacterial activity, they also exhibit cytotoxic effects on human cells. Our research focuses on understanding how the cells of the human immune system (both the innate response, namely HL-60 and U-937, and the acquired response, namely HUT-78 and COLO-720L) respond to the presence of zirconium (IV) oxide nanoparticles (ZrO2-NPs). Viability tests indicate that ZrO2-NPs exert the highest cytotoxicity on HL-60 > U-937 > HUT-78 > COLO 720L cell lines. Notably, concentrations exceeding 100 μg mL−1 of ZrO2-NPs result in significant cytotoxicity. These nanoparticles readily penetrate the cell membrane, causing mitochondrial damage, and their cytotoxicity is associated with heightened oxidative stress in cells. The use of ZrO2-NP-based materials may pose a risk to immune system cells, the first responders to foreign entities in the body. Biofunctionalizing the surface of ZrO2-NPs could serve as an effective strategy to mitigate cytotoxicity and introduce new properties for biomedical applications