Selective and smart dual-channel colorimetric sulfur ion sensing readout platform

Abstract

It is in urgent to develop a facile sulfur ion (S2-) detection platform with good selectivity, sensitivity and portability, since the abnormal concentration of S2- poses a serious threat to human health and environment. Nanozymes are expected as promising colorimetric probe for visual assays, but the selectivity is challenged since the mostly typical nanozymes are oxidoreductase-like ones while various analytes possess equivalent redox capacity. Herein, one-platform-two-channels detection method with both excellent selectivity and sensitivity was constructed based on the bifunctions of tin telluride (SnTe) nanobelts. On one hand, SnTe and S2- can react rapidly to form a special brown product SnS to assure the selectivity; On the other hand, SnTe with peroxidase-like activity can oxidize 3,3’,5,5’-tetramethylbenzidine (TMB) to blue ox-TMB in the presence of H2O2, while strong reducing S2- could inversely convert the solution from blue to colorless and then brown, enabling a wider range of S2- detection (10 nM-900 μM) and low detection limit of 7.1 nM. In addition, this detection platform could still show excellent specificity against 19 other interfering substances in sulfur soaps with complex components. With the assistance of the color-to-value conversion function of a smartphone, a portable signal reading-out platform was established, which can successfully achieve the accurate visualization of the S2− in 10 min