NiCo2S4 microflowers as peroxidase mimic: A multi-functional platform for colorimetric detection of glucose and evaluation of antioxidant behavior

The regular design of atomic composition of materials endows a diverse range of enzyme mimics types and increases a broader application prospect. In this study, we designed a nickel-cobalt mixed metal sulfide and demonstrated that the as-prepared NiCo2S4 microflowers possessed intrinsic peroxidase-like activity. Nickel-cobalt sulfide (NiCo2S4) possessed high electron transfer capacity, which lead to good peroxidase-like activity. Compared with the reported enzyme-like materials, NiCo2S4 exhibited a smaller Km and a stronger affinity with substrate. A colorimetric assay was developed for the direct detection of hydrogen peroxide and indirect detection of glucose over a wide linear range (H2O2 was 20–200 μM, and glucose was 20–1000 μM) with a low detection limit (H2O2 was 5.19 μM, and glucose was 8.24 μM). Furthermore, a NiCo2S4 based platform was established to study the antioxidant behavior of three antioxidants. The antioxidant capacities of the antioxidants were found to rank in the order: tannic acid (TA) > ascorbic acid (AA)> gallic acid (GA). Moreover, the three antioxidants showed different inhibition mechanisms. This study indicated a new and important application field for NiCo2S4 and provides a basis for the rational design of enzyme-like mimics in future research.