Simulated Enzyme Properties Of Spinel Sulfide And Their Applications In Analysis

Simulated enzymes are a kind of artificial enzyme mimics with characteristics of natural enzyme.They have the advantages of low cost,easy preservation,and stable properties.Therefore,it shows high application value in biochemical analysis and other fields.Nowadays,a large number of different types of natural enzymes have been mimicked by enzyme mimics.However,the rational design of enzyme mimic materials to obtain higher catalytic activity,and the development of new enzyme mimic types to expand the application range of enzyme mimics are still the focus of research.Spinel sulfide materials are a class of metallic sulfides with exchangeable metal sites in their structures,which enable them to obtain different properties by exchanging ion types.Moreover,the S atoms make it highly conductive.Therefore,spinel sulfides are widely used in the fields of battery and electrocatalysis.However,there are few reports on its application in the field of enzyme mimics and analysis.Based on the above discussion,the ionic composition of spinel sulfide was modulated and different types of mimetic enzymes were obtained.Then,the activities of different kinds of enzymes and their catalytic mechanism were investigated.A colorimetric/fluorescence detection platform was established and successfully used for the detection of real samples.(1)NiCo2S4 micro-flowers were prepared by a precursor method.The peroxidase activity and catalytic mechanism of NiCo2S4 microflowers were investigated.A colorimetric sensing platform established based on this showed high sensitivity to H2O2 and glucose,the limit of detection was 5.19 μM and 8.24 μM.The detection platform had been successfully used for the determination of glucose concentration in human serum samples.In addition,based on the inhibitory effect of antioxidants on the activities of peroxidase-like NiCo2S4,the antioxidant behaviors of tannic acid(TA),ascorbic acid(AA)and gallic acid(GA)was evaluated by using NiCo2S4-TMB-H2O2 system.The antioxidant capacities of the three antioxidants were:TA>AA>GA.And the three antioxidants present two different types of inhibition mechanisms:For AA,the inhibition comes from the strong electron transfer between AA and NiCo2S4.For GA and TA,the inhibitory effect stems from the competing reaction between antioxidants and TMB oxidized by H2O2.(2)One step synthesis of CuCo2S4 was achieved by hydrothermal method.The double enzyme activity(peroxidase(POD)and ascorbate oxidase(AAO))was investigated,which confirmed the possibility of CuCo2S4 as a tandem enzyme mimics.Based on this,the CuCo2S4 tandem simulated enzyme cascade detection platform was established for the determination of ascorbic acid,and the detection mechanism was discussed.Based on the AAO-like activity,CuCo2S4 catalyzed AA to generate DHAA and H2O2 firstly;then,H2O2 was decomposed to OH by POD-like CuCo2S4,and ·OH would react with the substrate benzoic acid to generate fluorescent producer.The experimental results show that the detection limit of this method is as low as 0.11μM,and the method can be used to detect AA in real samples simply and effectively.