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

Hydrogen peroxide (H2O2) 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 H2O2 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 (MnO2 NPs) at a specific ratio to produce a near-infrared (NIR) excited luminescent nanoprobe for H2O2 detection. Our results revealed that the MnO2 NPs tended to experience catalytic decomposition when exposed to H2O2, while the UCNPs were retained inside the PSMA encapsulation, causing recovery of the UCNP emission band at 470 nm in accordance with H2O2 concentration. This luminescence recovery was linearly dependent on H2O2 concentrations, yielding a limit of detection (LOD) of 20 nM. The easy-to-interpret H2O2 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 H2O2 in living organisms.