Ratio fluorescent hybrid probe for visualized fluorescence detection of H 2 O 2 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 (H 2 O 2 ) detection was developed. The probe was used to measure the H 2 O 2 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 H 2 O 2 in lettuce leaf, and realized the visualized fluorescence qualitative detection H 2 O 2 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 H 2 O 2, 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.