Impact of titanium dioxide particle size on macrophage production of intracellular reactive oxygen species

Objectives: The aim of this study was to investigate the response of THP-1 monocyte-derived macrophages following exposure to titanium dioxide nanoparticles (TiO2 NPs) and microparticles (TiO2 MPs) in an in vitro system. Design: THP-1 monocytes were maintained in RPMI medium and transformed into MO macrophages using Phorbol 12-myristate 13-acetate (PMA). TiO2 particle size characterization was performed using scanning electron microscopy (SEM) and dynamic light scattering (DLS) technology. A viability study using an XTT assay was performed by treating THP-1-derived macrophages with TiO2 NPs (<100 nm) and TiO2 MPs (<5 mu m) at concentrations ranging from 100, 50, 25, 12.5, 6.25 and 3.125 mu g/mL. Macrophages were then treated with three different concentrations of NPs and MPs (5, 20 or 100 mu g/mL) for 24 h, and ROS production and TiO2 particle cellular uptake were measured using ROS assays and flow cytometry, respectively. Results: There was no significant change in the viability of THP-1 monocytes after treatment with TiO2 NPs and MPs. The uptake of both particles was confirmed and showed an increase in ROS generation, and the MPs produced more ROS than NPs. The increase in ROS generation with NPs was concentration-dependent. Conclusion: Uptake of TiO2 NPs and MPs in macrophages at subcytotoxic levels generate ROS in a size- and dosedependent manner.

Automated summary

The study revealed that uptake of TiO2 nanoparticles and microparticles in macrophages at subcytotoxic levels generates ROS in a size- and dose-dependent manner.