Titanium dioxide nanoparticles: an in vitro study of DNA binding, chromosome aberration assay, and comet assay

Engineered titanium dioxide nanoparticles (TiO₂ NPs) are extensively used in cosmetic, pharmaceutical and other industries globally due to their unique properties, which has raised concern for biosafety. Genotoxicity assessment is an important part of biosafety evaluation; we report in vitro cytogenetic assays for NPs considering their unique physicochemical characteristics to fill the gap of laboratory data regarding biological safety along with mechanistic study for mode of interaction of NP with genetic material. Comet and chromosome aberration assay (CA assay) using short-term human peripheral blood cultures following exposure to TiO₂ NPs; along with physicochemical parameters for stability of nano form in cultures; and DNA binding activity were carried out. The dynamic light scattering and zeta potential measurements revealed mono dispersion in media. The fluorescence spectroscopy for binding affinity of TiO₂ NPs and human genomic DNA showed binding constant (K_b), 4.158 × 10⁶ M^-1 indicating strong binding affinity and negative ΔG⁰ value suggesting spontaneous DNA binding supporting its genotoxic potential. Following in vitro exposure to TiO₂ NPs for 24 h, the cultures were analyzed for comet and CA assays, which showed significant results (p < 0.05) for % DNA intensity in tail, Olive Tail Moment and frequency of Chromosomal aberrations (CA) at 75 and 125 μM but not at 25 μM.