Lighting up endogenous H2O2 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 (MnO₂) nanosheets, a sensitive and convenient dual-mode “turn on” bioimaging nanoprobe ZGC@MnO₂ has been developed for long afterglow imaging and MRI of endogenous hydrogen peroxide (H₂O₂) in the tumor microenvironment (TME). The monitoring of H₂O₂ 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 ZnGa₂O₄:Cr (ZGC) nanoparticles were synthesized as luminophores, and MnO₂ nanosheets were utilized as a fluorescence quencher, carrier and H₂O₂ recognizer. H₂O₂ in the TME could reduce MnO₂ nanosheets to Mn²⁺ for MRI, and ZGC nanoparticles were released for long afterglow imaging. Finally, the ZGC@MnO₂ nanoprobe exhibited a rapid response, an excellent signal-to-noise ratio and a limit of detection of 3.67 nM for endogenous H₂O₂ in the TME. This dual-mode approach enhances the detection sensitivity for endogenous H₂O₂, thereby facilitating the research of endogenous H₂O₂-associated diseases and clinical diagnostics.