2D CoOOH nanosheets as oxidase mimic for the colorimetric assay of sulfite in food

Abstract

Here, we report a rapid, sensitive and selective colorimetric assay for sulfite (SO₃²⁻) based on the intrinsic oxidase-like activity of 2D cobalt oxyhydroxide nanosheets (CoOOH NSs). The 2D CoOOH nanozyme could directly oxidize 3,3′,5,5′-tetramethylbenzidine (TMB) into blue products (TMB_ox) in an aerobic solution without H₂O₂. Interestingly, the presence of SO₃²⁻ could effectively inhibit the CoOOH NS–O₂–TMB reaction system and thus caused changes in color and absorbance, which facilitated a colorimetric sensor for sulfite. After optimizing detection conditions, a facile and robust approach was developed for SO₃²⁻ detection in food.