Lighting up endogenous H 2 O 2 in the tumor microenvironment using a dual-mode nanoprobe for long afterglow and MR bioimaging.

Persistent luminescent nanoparticles (PLNPs) are excellent luminescent materials, and near-infrared PLNPs are efficiently applied for biosensing and bioimaging due to their advantages of no excitation, excellent light stability and long afterglow. However, due to interference from the complex environment within organisms, single-mode imaging methods often face limitations in selectivity, sensitivity, and accuracy. Therefore, it is desirable to construct a dual-mode imaging probe strategy with higher specificity and sensitivity for bioimaging. Magnetic resonance imaging (MRI) has been widely used in the field of bioimaging due to its advantages of high resolution, non-radiation and non-invasiveness. Here, by combining near-infrared PLNPs and manganese dioxide (MnO 2 ) nanosheets, a sensitive and convenient dual-mode "turn on" bioimaging nanoprobe ZGC@MnO 2 has been developed for long afterglow imaging and MRI of endogenous hydrogen peroxide (H 2 O 2 ) in the tumor microenvironment (TME). The monitoring of H 2 O 2 has garnered significant attention due to its crucial role in human pathologies. For the dual-mode "turn on" bioimaging nanoprobe, the near-infrared PLNPs of quasi-spherical ZnGa 2 O 4 :Cr (ZGC) nanoparticles were synthesized as luminophores, and MnO 2 nanosheets were utilized as a fluorescence quencher, carrier and H 2 O 2 recognizer. H 2 O 2 in the TME could reduce MnO 2 nanosheets to Mn 2+ for MRI, and ZGC nanoparticles were released for long afterglow imaging. Finally, the ZGC@MnO 2 nanoprobe exhibited a rapid response, an excellent signal-to-noise ratio and a limit of detection of 3.67 nM for endogenous H 2 O 2 in the TME. This dual-mode approach enhances the detection sensitivity for endogenous H 2 O 2 , thereby facilitating the research of endogenous H 2 O 2 -associated diseases and clinical diagnostics.