Au/MnO2 Featuring Efficient Oxidase-mimic Activity at Neutral pH: Toward Portable Dual-modal Sensor for sulfide detection integrated with smartphone

The rapid detection of sulfide compounds including glutathione (GSH) and Na2S2O8 is of great interest because they play an essential role in the process of food processing. Here, we design a colorimetric/smartphone dual-mode sensing platform to detect GSH and Na2S2O8 simultaneously, depending on gold nanoparticle-decorated MnO2 nanosheets (Au/MnO2 NSs). Because of the distinct structure, Au/MnO2 possesses superior catalytic activity similar to native oxidase capable of catalysing the directly oxidation of 3,3’,5,5’-tetramethylbenzidine (TMB) under near-neutral pH conditions. Meanwhile, this catalytic reaction results in an obvious color change or the solution, which senses GSH and Na2S2O8 through redox and diazotization reactions. The designed sensor enables value-assisted and visual determination of GSH and Na2S2O8 with limits of detection of 2.3 nM. Based on the dual-modal sensing system, a smartphone-mediated “all-in-one” sensing platform is designed to realize the real-time and intelligent monitoring of GSH and Na2S2O8. This work provides a new avenue to construct multifunctional sensors to achieve the visualization and portable determination of sulfide compounds.