In Vivo Oxidative Stress Monitoring Through Intracellular Hydroxyl Radicals Detection by Recyclable Upconversion Nanoprobes.

Oxidative stress, as an essential cause to many diseases via irreversible biomolecule oxidation, can be induced by casual-contacted nanomaterials, which can generate hydroxyl radical (•OH) due to their active surface capacity. Herein, we report a novel upconversion nanoprobe for ratiometric •OH detection and monitoring titanium oxide nanomaterial-induced oxidative stress. Unlike previously developed nanoprobes, the •OH-responsive acceptor in these nanoprobes can be rapidly prepared and easily recycled. With a detection limit of ∼2 nM and a broad linear range of 4 nM-16 μM, the nanoprobe is suitable for both in vitro and in vivo applications. The facile preparation and recyclable strategy provide a new method for developing novel nanoprobes that can directly detect hazardous molecules in biological samples and systems.