The Enzyme-Like Activity Of Manganese Cobalt Oxide And Its Applications

As a traditional biocatalyst,natural enzymes can specifically and efficiently catalyze substrate reactions under mild conditions.However,natural enzymes are prone to denaturation and loss activation in harsh environments,which limits their wide applications.In order to overcome these shortcomings,artificial enzymes came into being.Nanozymes are a class of artificial enzymes,which not only have the unique properties of nanomaterials,but also have catalytic functions.Nanozymes have aroused great research interests due to their tunable catalytic activity,high stability and excellent biocompatibility.At present,nanozymes are widely used in industrial production,environmental management,biochemical testing,disease treatment and many other fields as an improssing alternative for natural enzymes.As an important branch of nanozymes,oxidase mimics can catalyze the oxidation of substrates without the participation of H₂O₂,and avoid the instability of enzyme activity caused by the decomposition of H₂O₂.Manganese dioxide is a common oxidase-like enzyme,but it suffer from poor stability and is easy to dissolve by reacting with reducing enzyme reaction substrates.At the same time,the conductivity of manganese dioxide is poor,which is unfavorable for electron transfer during the enzyme redox reaction.In addition,cobalt oxide has the advantages of high stability and low cost,and great progress has been made in the development and applications of nanozymes.However,the current reports focus on the peroxidase like activity of cobalt oxide,but its oxidase like activity is rarely reported.Many studies have confirmed that bimetallic oxides can not only overcome the inherent defects of single metal oxides,but also can impart new excellent properties to materials through the synergistic effect of bimetals.To address this issue,different manganese cobalt oxide were synthesized,and the inherent defects of single metal nanozymes were overcome by synergy.New colorimetric detection methods based on the oxidase like activity of manganese cobalt oxide were established.The main work includs as follows:1.Using manganese-cobalt Prussian blue analogues as the precursor,porous manganese-cobalt oxide microspheres(Mn_xCo_1-xO)with different manganese and cobalt compositions were prepared.The structure-activity relationship between the composition of Mn_xCo_1-xO and the activity of mimic oxidase was investigated.Under the optimal reaction conditions,the catalytic mechanism and kinetics were explored.Based on the fading effect of sulfide ion on ox TMB,a new sulfide ion colorimetric detection method was established,with a detection limit of 0.1μM（S/N=3）and a detection range of 0-25μM.This method has good selectivity and can be applied to the detection of sulfide ions in tap water.2.OVs-CMO with a large number of surface oxygen vacancies was prepared,and the oxidase-like activity of oxygen-vacancy rich OVs-CMO was explored.Under the optimal reaction conditions,the catalytic mechanism and kinetics were explored.Based on the electrostatic adsorption between the negatively charged heparin and the positively charged oxygen-vacancy enriched OVs-CMO,a new method for colorimetric detection of heparin was established with a detection limit of 0.2μM（S/N=3）and a detection range of 0-12μM.and the potential of this method in practical applications was explored.