Engineering a polymer-encapsulated manganese dioxide/upconversion nanoprobe for FRET-based hydrogen peroxide detection

Hydrogen peroxide (H 2 O 2 ) is considered a significant biomarker in various diseases and could induce deleterious health problems at irregular physiological concentrations. Therefore, developing a simple, efficient biocompatible nanoprobe for trace amount H 2 O 2 detection with high sensitivity and specificity is of great help for early diagnosis and therapeutics. Herein, we designed amphiphilic poly(styrene-co-maleic anhydride) (PMSA)-encapsulated nanoclusters composed of upconversion nanoparticles (UCNPs) and manganese dioxide nanoparticles (MnO 2 NPs) at a specific ratio to produce a near-infrared (NIR) excited luminescent nanoprobe for H 2 O 2 detection. Our results revealed that the MnO 2 NPs tended to experience catalytic decomposition when exposed to H 2 O 2 , while the UCNPs were retained inside the PSMA encapsulation, causing recovery of the UCNP emission band at 470 nm in accordance with H 2 O 2 concentration. This luminescence recovery was linearly dependent on H 2 O 2 concentrations, yielding a limit of detection (LOD) of 20 nM. The easy-to-interpret H 2 O 2 nanoprobe also proved high selectivity in the presence of other interfering substances, and biocompatibility and water-dispersibility, making it an ideal candidate for real-time detection of disease-related H 2 O 2 in living organisms. Graphical Abstract