Activatable Lanthanide Nanoprobes with Dye-Sensitized Second Near-Infrared Luminescence for in Vivo Inflammation Imaging

Lanthanide nanoparticles exhibit unique photophysical properties and thus emerge as promising second nearcence brightness hampers their construction of activatable NIR-II probes. Herein, we report the synthesis of dye-sensitized (ICG)) and their further development for in vivo activatable only shifts the optimal doping concentration of Nd3+ from 5 to 20 mol % but also leads to a 5-fold NIR-II enhancement relative to the ICG-free counterpart. Mechanistic studies reveal that such a luminescence enhancement of NaGdF4:Nd at high Nd3+ concentration is ascribed to an alleviated cross-relaxation effect due to the broad absorption of ICG and faster energy transfer process. Taking advantage of dye oxidation, the nanoprobes enable activatable NIR-II imaging of hypochlorous acid (ClO-) in a drug-induced lymphatic inflammation mouse model. This work thus provides a simple, yet effective luminescence enhancement strategy for constructing lanthanide nanoprobes at higher activator doping concentration toward activatable NIR-II molecular imaging.

Automated summary

We report a synthesis method for dye-sensitized fluorescent probes, which enhance the fluorescence performance of lanthanide nanoparticles at high doping concentration of Nd3+ by adding indocyanine green (ICG), enabling activatable second near-infrared (NIR-II) fluorescent imaging.