In Situ Activatable Ratiometric Nir-Ii Fluorescence Nanoprobe For Quantitative Detection Of H2s In Colon Cancer

As key characteristic molecules, several H2S-activated probes have been explored for colon cancer studies. However, a few ratiometric fluorescence (FL) probes with NIR-II emissions have been reported for the quantitative detection of H2S in colon cancer in vivo. Here, we developed an in situ H2S-activatable ratiometric nanoprobe with two NIR-II emission signals for the detection of H2S and intelligently lighting up colon cancer. The nanoprobe comprised a down conversion nanoparticle (DCNP), which emitted NIR-II FL at 1550 nm on irradiation with a 980 nm laser (F-1550Em,F- 980Ex). Further, human serum albumin (HSA) was combined with Ag+ on the surface of DCNP to form a DCNP@HSA-Ag+ nanoprobe. In the presence of H2S, Ag2S quantum dots (QDs) were formed in coated HSA, which emitted FL at approximately 1050 nm on irradiation with an 808 nm laser (F-1050Em,F- 808Ex) through an H2S-induced chemical reaction between H2S and Ag+; however, the FL signal of DCNP was stable at 1550 nm (F-1550Em,F- 980Ex), generating a H2S concentration-dependent ratiometric F-1050Em,F- 808Ex/F-1550Em,F- 980Ex signal. The NIR-II ratiometric nanoprobe was successfully used for the accurate quantitative detection of H2S and the detection of the precise location of colon cancer through an endogenous H2S-induced in situ reduction reaction to form Ag2S QDs. Thus, these findings provide a new strategy for the specific detection of targeted molecules and diagnosis of disease based on the in situ-activatable NIR-II ratiometric FL nanoprobe.