Electrochemical Sensors Based On Covalent Organic Frameworks For Food And Drugs Detection

As we all know,the safety of food and drugs will directly affect human health,especially with the rapid development of modern food industry and medicine industry,the types and quantities of food and drugs have increased sharply.As one of the world’s largest consumers of food and drugs,it is particularly important for China to develop fast and effective analytical methods to monitor food and drugs and control their safety.Electrochemical sensors are popular in food and drug analysis because they are small devices with simple operation and fast detection speed that are suitable for field applications.In recent years,covalent organic frameworks（COFs）have been developed rapidly.As a new electrode material,COFs have great potential application in the field of electrochemical sensors because of their large surface area,adjustable pore,good stability and biocompatibility.In this dissertation,four simple electrochemical sensors are constructed for the electrochemical detection of folic acid（FA）,bisphenol A（BPA）,amoxicillin（AMX）and acetaminophen（AP）respectively.The experimental contents are as follows:（1）Electrochemical sensor based on covalent organic framework for detection of folic acidTAPB-DMTP-COF was first synthesized with 1,3,5-tri（4-aminophenyl）benzene（TAPB）and 2,5-dimethoxybenzene-1,4-diformaldehyde（DMTP）as monomer.It was used as a modification material to construct an electrochemical sensor for the electrochemical detection of FA.The obtained COF was characterized by electron microscopy,X-ray diffraction（XRD）and Fourier transform infrared spectroscopy（FTIR）.The electrochemical experiments proved that TAPB-DMTP-COF owned good electrocatalytic effect towards oxidation of FA.Using differential pulse voltammetry（DPV）as detection method,under optimal conditions,the sensor exhibited a wide linear response range（1-800μM）to FA with a detection limit of 0.3μM.In addition,the sensor also exhibited strong anti-interference ability,good reproducibility and high recoveryfor real sample detection.（2）An electrochemical sensor based on covalent organic framework and cuprous oxide was developed for the determination of bisphenol AA sensitive electrochemical sensor for BPA detection was constructed using octahedral cuprous oxide（Cu₂O）and TAPB-DMTP-COF as modified materials.The Cu₂O/TAPB-DMTP-COF nanocomposites were characterized by scanning electron microscopy（SEM）,XRD,FTIR and X-ray photoelectron spectroscopy（XPS）.The electrochemical behavior of different modified electrodes was investigated via cyclic voltammetry.Owing to the synergistic effect between good catalytic activity of Cu₂O and porous structure of TAPB-DMTP-COF,the electrochemical sensor of Cu₂O/TAPB-DMTP-COF/GCE exhibits good electrocatalytic activity for electrochemical oxidation of BPA.The detection linear range for BPA is 0.5-50μM with the detection of limit of 0.17μM.In addition,the sensor exhibits good reproducibility,stability,and selectivity,together with the potential for real sample analysis.（3）Electrochemical sensor based on covalent organic framework loaded with FeCr₂O₄nanoparticles for highly sensitive detection of amoxicillinFeCr₂O₄/TAPB-DMTP-COF nanocomposite material was synthesized using FeCr₂O₄nanoparticles and TAPB-DMTP-COF nanomaterial,which was used as a new electrode modification material to prepare electrochemical sensor for AMX detection.The morphology and structure of the materials were characterized by XRD,FTIR,SEM and energy dispersive spectroscopy（EDS）.Due to the synergistic effect of the large surface area of the TAPB-DMTP-COF material and the high catalytic capacity of FeCr₂O₄ nanoparticles,the sensor shows excellent analytical performance for AMX.DPV experiments show that the sensor has a wide detection range（1-150μM）and a low detection limit（0.3μM）for AMX,the sensor has good selectivity and reproducibility,and also has good recovery rate in the actual sample detection.（4）Electrochemical sensor based on FeNi/rGO nanocomposites for highly sensitive detection of acetaminophenFeNi alloy nanoparticles were loaded on the surface of reduced graphene oxide（rGO）by ultrasound to obtain FeNi/rGO nanocomposites.The nanocomposites were analyzed by XRD,SEM,EDS and CV.Due to the good catalytic activity of FeNi alloy nanoparticles and the synergy between the high specific surface area and conductivity of rGO,FeNi/rGO nanocomposites showed excellent electrocatalytic effect on AP.DPV was used as the detection method.The detection linear range for AP is 1-100 and 100-3000μM,with the detection limit is 0.3μM.Moreover,the sensor also has good reproducibility,anti-interference and high recovery rate for actual sample detection.