| In recent years,nanozymes have attracted much attention because of their huge potential in the fields of biochemical analysis and environmental monitoring.Compared with natural enzymes,nanozymes have the advantages of stable chemical properties,low prices,and large-scale preparation.It is always the direction of the researchers to explore new nanozymes with high efficiency,stability and easy preparation,develop multienzyme activities,and study the catalytic mechanism.Binary metal oxides are able to synergistically enhance electron/ion conductivity and mechanical stability.Among them,Co-V-O nanomaterials(CoxV2O5+x,x=1,2,3)have attracted much attention owing to their complex crystal structures and magnetic properties,so they are often used as electrode materials and electrical catalyst.However,for a long time,its application is limited to the field of energy storage and optoelectronics,and there are few reports in the field of biochemical analysis.In view of this,we first investigated the nanozyme characteristics of Co-V-O nanomaterials,and studied the corresponding catalytic mechanism for different enzyme-like activities in this thesis.We also established a visual colorimetric sensor and a fluorescent biological platform,which were successfully applied to actual samples analysis and testing.The specific work content is as follows:(1)Cubic Co2V2O7 nanoparticles were synthesized using a simple hydrothermal method with pH regulation,and the triple-enzyme(oxidase-like,peroxidase-like,and catalase-like)activities and catalytic mechanisms of the prepared particles were systematically studied for the first time.Based on the oxidase-like activity of Co2V2O7 particles,a visual glutathione colorimetric sensor was established with a linear range of 2.5-20 ?M and a detection limit of 0.64 ?M.This method has been successfully applied to the detection of glutathione in health products.Based on the peroxidase-like activity of Co2V2O7 particles,a fluorescent biological platform was established for the detection of hydrogen peroxide and glucose,with linear ranges of 0.008-3.200 ?M and 0.1-80?M,and detection limits of 0.002 ?M and 0.03 ?M,respectively.The platform exhibits ultra-high sensitivity to hydrogen peroxide,which is far superior to most reports in the literature to date.In addition,this study establishes a novel one-step glucose detection strategy to replace the complex traditional two-step detection method,thereby making the detection process more efficient and convenient.This strategy has a high accuracy for the detection of human blood glucose.(2)Using CoCl2·6H2O and Na3VO4 as raw materials,Co3V2O8 nanospheres were synthesized by hydrothermal method.Using TMB as a substrate,the oxidase-like catalytic behavior was studied in detail,and its catalytic mechanism was discussed in depth.by means of cyclic voltammetry and EPR technology.The Michaelis-Menten kinetics experiment showed that Co3V2O8 nanoparticles have a high affinity for the substrate,and the Zeta potential test confirmed that Co3V2O8 nanoparticles combined with TMB through electrostatic interaction.In the oxidation process of TMB,dissolved oxygen participates in electron transfer as an electron acceptor.Co3V2O8 particles accelerate the catalytic transfer of electrons in the catalytic reaction to improve the catalytic efficiency.No active oxygen(·OH,O2·-)is produced during the reaction.We further investigated the material's own performance in the catalysis process.The results show that the materials synthesized in different batches have relatively stable catalytic activity,excellent reusability and storage stability.Based on the oxidase-like activity of Co3V2O8,a new colorimetric detection method for sulfite was established.This method has good selectivity to sulfite ions.Under the optimized conditions,the linear range for sulfite detection is 1-20 ?M,and the detection limit is 0.49 ?M.It has been successfully applied to the sulfite in edible sugar detection. |
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