Metabolomic Responses of Osteoblasts to Zirconia Nanoparticles Across Dose and Time

In this study, we investigated the dose- and time-dependent metabolic responses of human osteoblast-like cells following exposure to zirconia nanoparticles ZrO₂ NPs. Cells were treated with 0 10 25 50 and 100 µg mL ZrO₂ NPs for 24 and 72 h and analyzed using targeted liquid chromatography mass spectrometry based metabolomics. Cell viability reactive oxygen species production alkaline phosphatase activity and mineralized nodule formation were systematically evaluated. Cell viability remained above 90 percent at concentrations up to 50 µg mL whereas metabolomic analysis revealed significant alterations in glycolytic flux tricarboxylic acid cycle intermediates and glutathione metabolism with a false discovery rate below 0.05. Exposure to 100 µg mL ZrO₂ NPs led to increased oxidative stress reduced alkaline phosphatase activity and impaired mineralization. Partial least squares discriminant analysis demonstrated clear metabolic separation between control and treated groups with cysteine glutamate and citrate identified as key discriminatory metabolites. These results indicate that ZrO₂ NPs induce measurable metabolic modulation at sub toxic concentrations and affect osteogenic and redox related pathways in a concentration and time dependent manner.