Distinction of antioxidants using a three-channel colorimetric sensor array constructed with a bimetallic FeCo nanozyme

The antioxidant content in food is related to the dietary safety of consumers. In this context, two-dimensional (2D) iron/cobalt metal nanosheets (Fe/Co NSs) have been synthesized through the synergistic self-assembly reaction of Fe³⁺/Co²⁺ with terephthalic acid. These Fe/Co NSs exhibit excellent peroxidase-like activities. Based on the nanozyme property of Fe/Co NSs, a three-channel sensor array has been constructed using 3,3',5,5'-tetramethylbenzidine (TMB) as the colorimetric substrate and three wavelengths (370, 456, and 654 nm) as the array's channels, enabling distinct absorbance response signals for the identification of five antioxidants with 100% accuracy. The sensor array can accurately detect five antioxidants in the range of 100 nM-100 μM, achieving accurate quantitative analysis. The sensor array also has excellent anti-interference ability toward other interferents, even at high concentrations. These abilities endow the sensor array with great potential for discrimination of blind and actual antioxidant samples.