Oxidation etching induced dual-signal response of carbon dots/silver nanoparticles system for ratiometric optical sensing of H2O2 and H2O2-related bioanalysis.

Ratiometric sensing suffers from less interference and can obtain more accurate results than single-signal assay. Here, a new ratiometric optical sensing strategy for H2O2 detection is developed by etching silver nanoparticles (AgNPs) to deactivate fluorescence resonance energy transfer (FRET) and reduce Rayleigh scattering based on a hyphenated technique of fluorescence and second-order Rayleigh scattering (SRS). The ratiometric detection of H2O2 is achieved through exploiting a hybrid system fabricated by fluorescent carbon dots and silver nanoparticles (CDs/AgNPs). In the CDs/AgNPs system, the fluorescence of CDs is quenched because of FRET, and the scattering is strong due to the intrinsic high light-scattering power of AgNPs. With the introduction of H2O2, the AgNPs are etched and the CDs are released from the AgNP surface, resulting in the fluorescence enhancement and scattering decline. As a result, ratiometric sensing of H2O2 can be achieved based on the CDs/AgNPs system by simultaneous collection of fluorescence and SRS signals. The sensing system is further used for H2O2-generation bioanalysis, and as a proof-of-concept, ratiometric assay of glucose and evaluation of glucose oxidase activity are performed successfully. This work provides a new perspective for sensing applications of plasmonic nanoparticles.