A Metal-Organic Framework Electrochemical Biosensor For Organophosphorus Detection

The overuse of organophosphorus pesticides will cause environmental pollution and health risks.The structure of neurochemical warfare agents is similar to that of organophosphorus pesticides,which is highly toxic and harmful to the nervous system of the human body.Therefore,using organophosphorus pesticides as neurochemical warfare agents simulation agents to establish a simple,sensitive,rapid and economical organophosphorus sensing platform can not only alleviate people’s concerns about environmental protection and food safety,but also lay a good foundation for the detection and defense of chemical warfare agents.In recent years,the rapid development of nanotechnology,thanks to the good sensitivity and affinity of nanomaterials to biomolecules,electrochemical biosensor sensitivity,electrochemical activity and biocompatibility and other properties continue to improve.The purpose of this paper is to construct an efficient and sensitive electrochemical aptamer sensor and electrochemical enzyme sensor based on metal-organic framework（MOFs）nanomaterials for the detection of organophosphorus,a common organophosphorus pesticide isocarbophos（ICP）was used as the research objectand to study and evaluate its detection performance.The main research contents and results are as follows:（1）A label-free and enzyme-free electrochemical sensing platform for ICP was developed based on UiO-66-NH₂ and nucleic acid aptamers.Nucleic acid aptamer functionalized UiO-66-NH₂ composites were successfully prepared by physical mixing（non-public valence binding）and chemical binding（covalent binding）.Electrochemical nucleic acid aptamer biosensors Apt/UiO-66-NH₂/AuE and COOH-Apt@UiO-66-NH₂/AuE were constructed for the detection of organophosphorus pesticide isocarbophos（ICP）.The effect and principle of ICP detection were compared.The results show that the sensing performance of ICP detected by chemical combination mode is better than that by physical mixing mode.In physical mixing mode,the linear detection range of the sensor is 34.6 nM-3.46μM and the detection limit is 20.74 nM;while in chemical combination mode,the linear detection range of the sensor is 3.46 nM-3.46μM and the detection limit is 3.11 nM,the nucleic acid aptamer sensor has good anti-interference ability and repeatability,and the detection recovery rate of the actual sample is 91.3%-110.2%,showing a good accuracy.（2）An electrochemical detection platform for ICP was developed based on ZIF-8and ACh E.ZIF-8 nanoparticles were prepared by co-precipitation method,and ACh E-CS/GR/ZIF-8 composites were prepared by one-step method combined with graphene（GR）nanomaterials.An efficient and sensitive electrochemical enzyme biosensor ACh E-CS/GR/ZIF8/GCE was successfully constructed on glassy carbon electrode（GCE）.Isocarbophos（ICP）was detected by enzyme inhibition method.The results show that the acetylcholinesterase biosensor has a strong current response to the substrate,its Michaelis constant is 0.403 mM,the linear detection range of the sensor for ICP is 1.73-345.7 nM,and the detection limit is 0.62 nM.The enzyme sensor has good anti-interference ability and repeatability,and can be used for the sensitive detection of isocarbophos in actual samples,and the recovery rate is 88.1%-122.4%.The electrochemical aptamer sensor and electrochemical enzyme sensor constructed in this paper provide a reference strategy for the efficient immobilization of aptamer and enzyme onMOFs,and have good sensing performance.