Real-time in vivo ROS monitoring with luminescent nanoparticles reveals skin inflammation dynamics

Reactive oxygen species (ROS) are key regulators in numerous pathological contexts, including cancer or inflammation. Their role is complex, which justifies the need for methods enabling their quantitative and time-resolved monitoring in vivo, in the perspective to profile tissues of individual patients. However, current ROS detection methods do not provide these features. Here, we propose a new method based on the imaging of lanthanide-ion nanoparticles (GdVO₄:Eu), whose photoluminescence is modulated by the surrounding ROS concentration. We monitored their luminescence after intradermic injection in a mouse ear submitted to an inflammation-inducing topical stimulus. Based on this approach, we quantified the ROS concentration after inflammation induction and identified a two-step kinetics of ROS production, which may be attributed to the response of resident immune cells and their further recruitment at the inflammation locus.