Intrinsic Peroxidase-mimics Activity Of Hollow (Zn)/Co-ZIF And Its Derivative In The Biochemical Assay Of Dopamine And Glucose

Enzyme is a kind of biocatalyst,which affects many catalytic processes,such as metabolism,nutrition and energy conversion.Because of its high specificity and efficiency,good selectivity under mild conditions,it has important applications in many fields,such as industry,food,agriculture and disease diagnosis.However,there are inherent defects in natural enzymes,such as high cost,poor stability,complex purification process and harsh storage conditions,which limit their further application and development.Therefore,much attention has been paid to the nanomaterials with the activity of enzyme-likes.Since the Yan's group found Fe₃O₄ magnetic nanoparticles with intrinsic mimetic peroxidase activity in 2007.A variety of synthetic nanomaterials,such as single metal nanoparticles,bimetallic composite nanomaterials,carbon materials,metal oxide and metal sulfide nanomaterials have been discovered to possess enzyme-like activity,and have been widely used in immunological detection,biosensor,organic catalysis,adsorption and degradation of pollutants,etc.Compared with natural enzymes,the nanomaterials have the advantages of simple preparation method,strong environmental tolerance,low cost of preservation and preparation.In recent years,it has been reported that metal-organic frameworks?MOFs?and their derivatives also have mimic enzyme activities and are used in colorimetric biosensing due to their large specific surface area,adjustable pore structure,and abundant catalytic sites.MOFs and their derivatives have great potential in biomedical applications.Based on the enzyme-like activities of hollow Co-ZIF,hollow Zn/Co-ZIF and its carbonized derivatives derived from ZIF-67,a method for the analysis and detection of dopamine and glucose has been constructed.The specific contents are as follows:?1?Hollow Co-ZIF with oxidase-like catalytic activity and its applications for dopamine detection.In this chapter,we demonstrate a solvothermal reaction synthetic strategy for the fabrication of hollow Co-ZIF?H-Co-ZIF?which exhibits oxidase-like activity.The as-prepare H-Co-ZIF can effectively catalyze the oxidation of 3,3?,5,5?-tetramethylben-zidine?TMB?in the presence of dissolved oxygen in slightly acidic solution.By means of SEM,TEM,XRD,and XPS characterization methods,the morphology,crystal characteristics,and the valence state of metallic cobalt was analyzed.Kinetic studies indicated that H-Co-ZIF behaved an excellent affinity to TMB with K_m value of 0.0272mM.According to the radical capture results,it was further confirmed that O₂^·-and ¹O₂are the main active species in the catalytic reaction.As dopamine?DA?inhibits the oxidation of TMB,a colorimetric assay was developed for the detection of dopamine in a linear range of 0.02-10?M with a detection limit of 0.012?M.And this method was applied to the detection of dopamine hydrochloride injection and human blood samples with a better recovery rate.?2?The intrinsic peroxidase-like activity hollow Zn/Co-ZIF and its application in the detection of glucose.In this chapter,we have synthesized a hollow structure ZIF-67@ZIF-8?H-Zn/Co-ZIF?with peroxidase-like activity by etching core shell ZIF-67@ZIF-8 with methanol under heating conditions.The morphology,structure and elements of the material were analyzed by means of FTIR,SEM,TEM,EDS and XRD,which showed that the synthesized material still maintained a rhombic dodecahedral structure after the solvothermal synthesis.Steady-state kinetics experiments demonstrated that the reaction of H₂O₂ oxidized TMB catalyzed by H-Zn/Co-ZIF was in accordance with the Michelis-Menten kinetics model,and the free radical capture experiment further indicates that·OH and O₂^·-are the active oxygen intermediates in the catalytic process.Compared with natural enzyme,the material of this experiment is simple and stable.And it still preserved good catalytic activity when incubated at a temperature of 0-90°C and a pH of 2-10 for 2 h.Based on this,a simple and rapid method was developed for detection of H₂O₂,glucose and glucose oxidase?GOx?activity,in which the linear range of H₂O₂ is 0.1-100?M with a detection limit of 0.078?M,and glucose could be linearly detected in the range from 1 to 200?M with a detection limit of 0.83?M.The proposed methed was successfully applied to the determination of glucose content in human serum.?3?Peroxidase-like activity of hollow Zn/Co-ZIF carbonated derivatives and its application in glucose detection.In this chapter,we have prepared hollow Zn/Co-ZIF under Ar atmosphere and calcined at 400°C for 2 h to obtained the Co/ZnO-ZIF with peroxidase-like property.Similar to natural enzymes,the catalytic activity of Co/ZnO-ZIF is affected by pH and temperature,and the optimum conditions are pH 4 and 40°C.Compared with the materials before calcination,the Michaelis constant K_m with H₂O₂ as substrate is 0.038mM,which is 14 times lower than that before calcination?0.553 mM?,which shows stronger affinity with H₂O₂.Glucose oxidase can catalyze the oxidation of glucose to produce H₂O₂ quantitatively under the condition of oxygen.Based on this,a simple,highly sensitive and selective colorimetric assay was established for the detection of glucose.The linear range of glucose is 1-200?M with a detection limit of 0.83?M and it has achieved the accurate determination of glucose in serum based on the high catalytic activity of Co/ZnO-ZIF.