Mechanistic characterization of titanium dioxide nanoparticle-induced toxicity using electron spin resonance

Titanium dioxide nanoparticles (TiO(2) NPs) are one of the most widely used nanomaterials that have been manufactured worldwide and applied in different commercial realms. The well-recognized ability of TiO(2) to promote the formation of reactive oxygen species (ROS) has been extensively studied as one of the important mechanisms underlying TiO(2) NPs toxicity. As the "gold standard" method to quantify and identify ROS, electron spin resonance (ESR) spectroscopy has been employed in many studies aimed at evaluating TiO(2) NPs safety. This review aims to provide a thorough discussion of current studies using ESR as the primary method to unravel the mechanism of TiO(2) NPs toxicity. ESR spin label oximetry and immune-spin trapping techniques are also briefly introduced, because the combination of spin trapping/labeling techniques offers a promising tool for studying the oxidative damage caused by TiO(2) NPs.