Research For The Detection Of Hydrogen Peroxide Based On Novel Metal Organic Framework Nanozymes Electrochemical Sensor

Hydrogen peroxide（H₂O₂）participate in many physiological processes.Many signal transduction pathways and cell growth regulation are affected the dynamic balance of H₂O₂.The level of H₂O₂ is also closely related to the physiological and pathological conditions of organisms and is considered as the detection index of many diseases.Therefore,the detection of H₂O₂ will help to further understand its relationship with the physiological and pathological changes of the organism.The changes of the body can be confirmed quickly and accurately,and the determination of H₂O₂ is more conducive to the steady-state intervention of the internal environment and early diagnosis of diseases.Compared with other methods,electrochemical sensors perform many advantages,such as low cost,simple structure,high selectivity,high sensitivity and good stability.Owing to these advantages,electrochemical sensors are regarded as an ideal technology for the detection of active small molecules in biological samples.At the same time,the modification of nanomaterials promotes the development of electrochemical sensors and extends the application of detection for disease indicators.Among the numerous nanomaterials,nanomaterials with catalytic activity similar to natural enzymes are defined as nanozymes.Nanozymes overcome the disadvantages of easy inactivation and difficult preparation.Thus,they are favored in the detection of small molecules such as H₂O₂.It was found that some metal organic frameworks（MOFs）nanomaterials have enzyme like activity and can catalyze related reactions.Modified with MOFs,the detection sensitivity of the electrochemical sensors can be improved.Moverover,MOFs have large specific surface area,controllable size and pore size and excellent thermal stability,which further increase the advantages of electrochemical sensors.Therefore,the novel electrochemical sensors based on metal organic framework nanoenzyme were constructed.The detection of H₂O₂ in serum samples or released from cells was studied.The research and investigation contents of this dissertation can be summarized as the following two parts:（1）Electrochemical analysis of H₂O₂ by ternary metal organic framework material Ni Co M（M=Cu,Fe,Zn）The catalytic performance of metal MOFs Ni Co M（M=Cu,Fe,Zn）for H₂O₂ has been studied.The morphology of each material and electrochemical behavior on H₂O₂ were explored.The results show that four kinds of materials both have obvious response to H₂O₂ in 1 M KOH.The cyclic voltammetric peak current and current time（i-t）response of Ni Co Fe/GCE to H₂O₂ are the largest,indicating the best catalytic effect.Then,the effects of the amount of Ni Co Fe modification,scanning rate and i-t detection voltage on the detection were investigated.Under the optimum conditions,Ni Co Fe/GCE showed a good linear relationship between the signal and the concentration of H₂O₂ in the range of 5.0-100μM,400-1500μM,1.5-15 m M and the detection limit（LOD,S/N=3）was 2.1μM.At the same time,Ni Co Fe/GCE has good anti-interference,reproducibility,repeatability and stability,and successfully realized the detection of hydrogen peroxide in serum samples.（2）Construction of an electrochemical sensor for detecting H₂O₂ released by breast cancer cells MCF-7 based on MOFs derivativesTo detect H₂O₂ released from breast cancer cells after drug stimulation,a novel H₂O₂ enzyme-free electrochemical sensor based on MIL-68-NH₂（In）derived oxide was constructed.After calcination,In₂O₃,a derivative obtained from MIL-68-NH₂（In）,exhibits better catalytic activity because of larger surface area and better conductivity.And the In₂O₃ obtained from calcination for 3 hours performed the best electrocatalytic to H₂O₂.At the same time,in order to further improve the detection sensitivity and realize the detection of H₂O₂ released by cells,the glassy carbon electrode（GCE）was first modified with two-dimensional molybdenum disulfide（Mo S₂）nanosheets to load more MOF materials and platinum nanoparticles（Pt NPs）were modified by electrodeposition to improve the conductivity and stability of the electrochemical sensor.Under optimal conditions,the linear range of the sensor for H₂O₂ concentration detection is 10.0 n M-18.3 m M,and the limit of detection is 6.3 n M（S/N=3）.Pt/In₂O₃/Mo S₂/GCE was successfully applied to monitor the H₂O₂ released by MCF-7 breast cancer cells in real time.The experimental results show that the MOF-derived materials exisit a strong advantage and potential in improving the sensitivity of the sensor for real-time monitoring of the physiological process of disease markers.