Selective Colorimetric Detection of Hydrogen Sulfide Based on Primary Amine-Active Ester Cross-Linking of Gold Nanoparticles

Hydrogen sulfide (H₂S) is a highly toxic environmental pollutant and also an important gaseous transmitter. Therefore, selective detection of H₂S is very important, and visual detection of it with the naked eye is preferred in practical applications. In this study, thiolated azido derivates and active esters functionalized gold nanoparticles (AE-AuNPs)-based nanosensors have been successfully prepared for H₂S perception. The sensing principle consists of two steps: first, H₂S reduces the azide group to a primary amine; second, a cross-linking reaction between the primary amine and active ester induces the aggregation of AuNPs. The AE-AuNPs-based nanosensors show high selectivity toward H₂S over other anions and thiols due to the specific azide-H₂S chemistry. Under optimal conditions, 0.2 μM H₂S is detectable using a UV-vis spectrophotometer, and 4 μM H₂S can be easily detected by the naked eye. In addition, the practical application of the designed nanosensors was evaluated with lake water samples.