Au/AgI Dimeric Nanoparticles for Highly Selective and Sensitive Colorimetric Detection of Hydrogen Sulfide

Abstract The development of Au/AgI dimeric nanoparticles (NPs) is reported for highly selective colorimetric detection of hydrogen sulfide (H 2 S). The detection mechanism is designed by taking advantage of the chemical transformation of AgI to Ag 2 S upon reacting with sulfide, which leads to a shift in the plasmonic band of the attached Au NPs. The plasmonic shift is accompanied by a color change of the solution from purplish red to blue and finally to light green depending on the concentration of sulfide, thus enables a naked‐eye readout and UV–vis quantitation of the sulfide exposure. The Au/AgI dimeric NPs are further immobilized in agarose gels to produce test strips, which can be used for both naked‐eye readout and quantitative detection of sulfide using UV–vis spectroscopy thanks to its transparency in the visible region. Compared to commercial Pb(Ac) 2 test papers, the agarose gel strip has superior performance for detecting sulfide in terms of sensitivity, selectivity, stability, and fidelity. The agarose gel is also capable of detecting gaseous H 2 S at important concentration thresholds, suggesting its practicability in real life applications. The potential of agarose gels is further highlighted by its ability in the enrichment and colorimetric detection of gaseous H 2 S released during cell cultivation.