Titanium Dioxide Nanoparticle (TiO₂ NP) Induces Toxic Effects on LA-9 Mouse Fibroblast Cell Line

Titanium dioxide nanoparticles (TiO₂ NPs) are extensively applied in the industry due to their photocatalytic potential, low cost, and considerably low toxicity. However, new unrelated physicochemical properties and the wide use of nanoparticles brought concern about their toxic effects. Thereby, we evaluated the cytotoxicity of a TiO₂ NP composed of anatase and functionalized with sodium carboxylate ligands in a murine fibroblast cell line (LA-9).

Scanning Electron Microscopy (SEM), Dynamic Light Scattering (DLS), and ATR-FTIR spectroscopy were applied to determine nanoparticle physicochemical properties. The cell viability (MTT assay) and clonogenic survival were analyzed in fibroblasts exposed to TiO₂ NP (50, 150, and 250 µg/mL) after 24h. Moreover, oxidative stress, proinflammatory state, and apoptosis were evaluated after 24h.

TiO₂ NP characterization showed an increased hydrodynamic size (3.57 to 7.62 nm) due to solvent composition and a heterogeneity dispersion in water and cell culture media. Also, we observed a zeta potential increased from -20 to -11 mV in function of protein adsorption. TiO₂ NP reduced fibroblast cell viability and induced ROS production at the highest concentrations (150 and 250 µg/mL). Moreover, TiO₂ NP reduced the fibroblasts clonogenic survival at the highest concentration (250 µg/mL) on the 7th day after the 24h exposure. Nevertheless, TiO₂ NP did not affect the fibroblast proinflammatory cytokines (IL-6 and TNF) secretion at any condition. Early and late apoptotic fibroblast cells were detected only at 150 µg/mL TiO₂ NP after 24h.

Probably, TiO₂ NP photocatalytic activity unbalanced ROS production which induced apoptosis and consequently reduced cell viability and metabolic activity at higher concentrations.