Study Of Two Dimensional Material Ti₃C₂ MXene Immobilized Natural Enzyme And Nanozyme

MXene is a family of two-dimensional(2D)early transition metal carbides and carbonitrides with an accordion sheet structure.MXene was prepared by extracting the A atomic layer in the MAX phase.MXene is powerful hydrophilic as hydrophilic groups such as—O,—OH and—F are introduced during the preparation process.which gives it wide application in the fields of energy storage,catalysis,biomedicine and and other fields.In this paper,the effect of immobilization of natural enzymes and nanozymes onto MXene was investigated,and a platform for the cascade of natural enzymes and nanozymes was constructed and is described as follows:The effect of immobilization of papain by physical adsorption onto Ti₃C₂MXene has been investigated in this study.The immobilization conditions are optimized and the results show that the immobilized papain showed better stability at pH 6.5 in PBS buffer,immobilization time of 20 h,immobilization temperature of 10?and papain concentration of 2 mg·m L^-1 with an immobilization amount of 150 mg·g^-1 and a maximum enzyme specific activity of1701 U·g^-1.The Michaelis constant of the physical adsorption immobilized enzyme is 4243.18?g·m L^-1,the physical adsorption immobilised papain show a higher affinity for the substrate casein compared to the chemically cross-linking immobilized papain,while the affinity of the enzyme was reduced by the chemical cross-linking immobilized papain.The peroxidase-like properties of the compound of Ti₃C₂ MXene loaded with Fe₃O₄ has been investigated.The Fe₃O₄/Ti₃C₂ MXene catalyzes hydrogen peroxide to oxidize colourless 3,3',5,5'-tetramethylbenzidine(TMB)to blue ox TMB for colour reaction,and the Fe₃O₄/Ti₃C₂ MXene nanozyme has excellent catalytic stability and resistance to interference.Steady-state kinetic experiments show that the Fe₃O₄/Ti₃C₂ MXene nanozyme have better affinity for the substrate TMB,and the catalytic mechanism of Fe₃O₄/Ti₃C₂ MXene has been investigated.The Fe₃O₄/Ti₃C₂ MXene nanozyme-based platform for the colorimetric detection of hydrogen peroxide is developed by simply applying Fe₃O₄/Ti₃C₂ MXene nanozyme and TMB dropwise on qualitative filter paper to produce hydrogen peroxide test strips.A paper-based sensor for the real-time,rapid and sensitive quantitative detection of hydrogen peroxide is constructed based on the hydrogen peroxide test paper combined with a smartphone and colour analysis software,with linear range of 0.1?20 mmol·L^-1.The uricase and Fe₃O₄/Ti₃C₂ MXene nanozyme cascade reaction system has been established for the detection of uric acid by immobilizing uricase onto Fe₃O₄/Ti₃C₂ MXene nanozyme.The uric acid detection platform has been transferred to qualitative filter paper and combined with smartphone to construct uric acid paper-based sensor for portable detection of uric acid in the concentration range of 0.01 to 2 mmol·L^-1.