Tailoring the Enzyme-Mimetic Activity and Surface Nanostructure of Metal-Phenolic Platform for Colorimetric Detection of l-Cysteine

Green synthesis of multienzyme-like materials with low energy consumption and high economic added value remains challenging; thus, exploring economical and environmentally friendly strategies to develop multienzyme-like platforms is of great significance. Herein, a biomass (polyphenols)-based strategy to develop cost-efficient and high-performance platforms (manganese-tannic acid enzyme mimics, TAnc-Mnx-y platforms) with multienzyme-mimetic capacities is developed via the mineralization of metal–phenolic networks (MPNs) in an aqueous solution. This green synthesis strategy requires only water as a solvent and polyphenols and metal ions as feedstocks and requires no additional energy supply, making it simple and cheap. The mineralization process realizes the generation of MnOx-TA petals, which endows TAnc-Mnx-y with the flower-like surface, therefore enhancing the surface area and pore size. Benefiting from the flower-like surface and MnOx active sites, TAnc-Mnx-y with enhanced surface area and pore sizes displays exceptional oxidase (OXD)-, peroxidase (POD)-, and catalase (CAT)-mimetic activities. Excitingly, TAnc-Mnx-y could realize fast l-cysteine detection owing to their excellent OXD-mimetic activity. Colorimetric studies of TAnc-Mnx-y have shown a relatively wide detection range (8.26–90.86 μM), a fast detection speed (2 min), and a significantly low detection limit (2.28 μM) for l-cysteine detection. Moreover, TAnc-Mnx-y displays remarkable resistance to harsh environments and excellent selectivity among the other amino acids. In addition, the blood experiments also confirm the excellent biocompatibility of TAnc-Mnx-y. We believe that this study not only overcomes the current limitation of the synthesis for multienzyme-like nanoplatforms but also provides interesting insights for developing sensitive and selective methods for l-cysteine detection.