Ratio fluorescent hybrid probe for visualized fluorescence detection of H2O2 in vitro and in vivo

A silicon oxide quantum dots (Si-O QDs) and Ag nanoclusters hybrid nanosensing probe with dual-emission and small nanocrystals that acts as an "off-on" ratio fluorescent probe for hydrogen peroxide (H2O2) detection was developed. The probe was used to measure the H2O2 concentration generated by mitochondria in vitro via recording the I-455/I-680 fluorescence ratio. Furthermore, this hybrid probe was applied to monitor the wound-induced H2O2 in lettuce leaf, and realized the visualized fluorescence qualitative detection H2O2 in vivo via laser scanning confocal microscope. The working mechanism of the probe is also investigated. Inner filter effect (IFE) estimation, Fourier transform infrared (FTIR) spectra and high-resolution transmission electron microscopy (HRTEM) images were applied to study the quenching mechanism and recovering reason of Si-O QDs fluorescence. The results show that the blue fluorescence of Si-O QDs can be quenched by Ag NCs via the IFE and fluorescent resonance energy transfer (FRET) effect. After adding H2O2, the surface groups of Ag NCs was changed and the IFE and FRET effects between the Si-O QDs and Ag NCs are disabled, thus the quenched Si-O QDs luminescence can be regularly recovered.