Antioxidant Recognition by Colorimetric Sensor Array Based on Differential Etching of Gold Nanorods and Gold Nanobypyramids

The effective recognition of antioxidants is considered to have far-reaching significance in medical diagnosis. Here, an efficient visual sensing strategy is developed to identify multiple antioxidants, which takes advantage of the etching of two gold nanomaterials (i.e., Au nanorods (Au NRs) and Au nanobipyramids (Au NBPs)) by the oxidation product (TMB2+) of tetramethylbenzidine (TMB). TMB is oxidized to TMB2+, catalyzed by horseradish peroxidase (HRP), and TMB2+ can etch Au NRs and Au NBPs, resulting in the changes in the wavelength and color of the solution. Various antioxidants react with TMB2+ to varying degrees, resulting in different amounts of remaining TMB2+ and causing different degrees of Au etching, which realized the discrimination and determination of the eight antioxidants with a limit of detection of 100 nM. Importantly, our sensor array also showed excellent practical application capability in human serum samples.