Non-metallic plasmon-assisted upconversion fluorescence for ultrasensitive hydrogen peroxide detection from nM to μM.

Precise monitoring and quantification of H2O2 is highly urgent and of great significance for biomedicine, food safety, environmental monitoring, etc. Herein, we proposed a facile near-infrared (NIR) excited fluorescent probe composed of upconversion nanoparticles (UCNPs) and non-metallic plasmonic WO3-x for ultrasensitive quantitative H2O2 detection. Plasmonic WO3-x with oxygen vacancy-induced LSPR achieved over 680-fold enhancement of upconversion fluorescence at 520 nm, and also acts as the sensitive recognition site for H2O2. H2O2 quenched the LSPR band of plasmonic WO3-x, further significantly influencing adjacent fluorescence signals depending on its concentration. The probe exhibits a good linear response to H2O2 with a low detection limit (10-9 M) and a wide concentration range (0-50 μM), and shows satisfactory application in the determination of H2O2 in blood and milk. This work may provide new ideas for the development of non-invasive fluorescent nanoprobes and plasmon-assisted biochemical detection methods.