| 2,4-Dichlorophenoxyacetic acid（2,4-D）is a phenoxy organic pesticide that is widely used in agriculture because of its low price and strong weed control properties.However,due to poor biodegradability,there are a large number of residues in the environment.2,4-D remaining in the environment is enriched in the human body through the food chain,which can induce soft tissue sarcomas,endocrine system disorders and fetal malformations,and may also cause a series of ecological and environmental pollution problems.Therefore,it is of great significance to establish a new method and technology for the rapid and sensitive detection of 2,4-D in the environment.Due to excellent properties,such as good electrical conductivity,large specific surface area,easy synthesis and stable chemical properties,nanocomposites have been widely used in the analysis and detection of pesticides,hormones and other environmental pollutants.Molecularly imprinted polymers（MIPs）are a class of polymers that have the ability to identify the molecule of interest,while electrochemical analysis is easy to operate,fast and efficient.Combining the specific recognition ability of MIPs with nanocomposites for electrochemical analysis,the electrochemical sensors constructed have the advantages of high sensitivity and high selectivity.In this paper,molecularly imprinted polymers were successfully prepared using 2,4-D as template molecule,acrylamide（AM）,o-phenylenediamine（OPD）,methacrylic acid（MAA）as functional monomers,and using silica-based and stannic oxide-based nanomaterials as carriers to enhance electrochemical signals.A series of electrochemical sensors were constructed by combining it with an electrochemical workstation and successfully applied to the analysis and detection of pesticide 2,4-D.The research was mainly carried out from the following aspects:1.Development and application of 2,4-D imprinted electrochemical sensors with multi-walled carbon nanotubes coated with silica:MWCNTs-Si O2 was prepared and the surface was modified.Molecularly imprinted polymers were prepared by radical polymerization with modified MWCNTs-Si O2 as carrier,AM as functional monomer,and 2,4-D as template molecule.The morphology,structure and properties of the materials were characterized by multiple methods.Subsequently,it was modified as a sensing element on a glass-carbon electrode and successfully prepared an electrochemical sensor in combination with an electrochemical workstation.Under the optimized conditions,the linear detection range of the sensor is1.0×10-4～1.0×10-8mol L-1,and the detection limit is 4.27×10-9mol L-1.Finally,the sensor was used to analyze and detect 2,4-D in real samples with great success（milk,lake water）.2.Development and application of hierarchical porous silica-doped gold nanoparticles-modified 2,4-D imprinted electrochemical sensor:HPSNs-NH2@Au NPs were synthesized and modified on the surface of glassy carbon electrode as a carrier.Molecularly imprinted polymer was effectively synthesized by electropolymerization utilizing OPD as a functional monomer and2,4-D as a template molecule,and an electrochemical sensor was successfully created employing it as a sensing element and electrochemical workstation.The morphology,structure and properties of the materials were characterized by various methods.Under the optimized conditions,the linear detection range of the sensor is 10-4～10-11 mol L-1,and the detection limit is3.32×10-12mol L-1.Finally,the sensor was successfully applied to analyze and detect 2,4-D in real samples（milk,lake water,tap water）.3.Development and application of 2,4-D imprinted electrochemical sensor modified by tin dioxide doped silver nanoparticles:Ag/Sn O2 was synthesized and modified on the surface of ITO as a carrier.MAA was used as a functional monomer and 2,4-D was used as a template molecule to create molecularly imprinted polymers.Subsequently,the MIPs were driped onto the modified ITO surface as the sensing element,and the electrochemical sensor was successfully prepared in conjunction with the electrochemical workstation.The morphology,structure and properties of the materials were characterized by different methods.Under the optimized conditions,the linear detection range of the sensor is 5×10-4～5×10-11 mol L-1,and the detection limit is 2.13×10-11mol L-1.Finally,the sensor was successfully applied to detection 2,4-D in real samples（milk,tap water）.In summary,three molecularly imprinted electrochemical sensors were prepared using MWCNTs-Si O2,HPSNs-NH2@Au NPs,and Ag/Sn O2 nanocomposites as carrier materials.The sensor has the characteristics of high sensitivity,high selectivity and stability,and can be used for the analysis and detection of 2,4-D in actual samples.It has potential application value in pesticide monitoring and analysis. |
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