In vitro biological response of micro- and nano-sized monosodium titanates and titanate-metal compounds.

Previous studies report that microsized monosodium titanates (MSTs) deliver metal ions and species to mammalian cells and bacteria with cell-specific and metal-specific effects. In this study, we explored the use of MST and a new synthesized nanosized monosodium titanate (nMST) to deliver gold(III), cisplatin, or platinum(IV) to two human cell lines with different population doubling times, in vitro. The effect was measured using a fluorescent mitochondrial activity assay (CellTiter-Blue(®) Assay). This fluorescence assay was implemented to mitigate optical density measurement errors owing to particulate titanate interference and allowed for the studies to be extended to higher titanate concentrations than previously possible. Overall, native MST significantly (p < 0.05) decreased mitochondrial activity of both cell types by 50% at concentrations of >50 mg/L. Native nMST significantly suppressed the rapidly dividing cell line (by 50%) over untreated cultures, but had no effect on the more slowly dividing cells. For both cell types, increased titanate concentrations resulted in increased effects from delivered metals. However, there was no difference in the effect of metal delivered from micro- versus nano-sized MST.