Molecularly Imprinted Electrochemical Or Colorimetric Sensors Based On Metal-organic Framework Derivatives For Detections Of Pesticide Residues And Antibacterial Drugs

Metal-organic frameworks（MOFs）are a class of porous organic-inorganic hybrid crystalline compounds formed by the self-assembly of metal ions/metal clusters and organic bridging ligands through coordination.The advantages of the specific surface area,orderly pores,adjustable components and structure have now been widely used in the development and preparation of multifunctional porous materials.The transition metal nodes（such as Zn,Co,Cu）contained in MOFs are processed by the special means to derive a wealth of catalytically active sites.The unique structure and large specific surface area of MOFs are conducive to contact and enrichment of substrates.Therefore,the preparation of catalytic materials using MOFs as precursors has become a rapidly developing emerging research field in recent years.Sensor technology,especially electrochemical sensors and colorimetric sensors,has the advantages of high sensitivity,simple operation,rapid response,and low detection cost,and is widely used in the fields of drug quality control,food safety,and environmental monitoring.This article aims to use metal-organic framework compounds as precursors to prepare the metal oxide（sulfide）compound materials,and combined with molecular imprinting technology,to construct electrochemical sensors and colorimetric sensors with excellent performance for detections of residual pesticides and antibacterial drugs.The main content of the paper is as follows:（1）In the second chapter experiment,for the first time,CoS nanoparticles attached ZnS rods（CoS/ZnS composites）have been synthesized using cobalt（II）-ion-exchanged zinc-based biological metal-organic framework-1（Zn-bio-MOF-1）as precursors by a solvothermal method.Among them,the cobalt（II）-ion-exchanged Zn-bio-MOF-1 was obtained by exchanging the dimethylammonium cations(Me²NH²⁺)of Zn-bio-MOF-1 with cobalt ions.The CoS/ZnS composite material was modified on the glassy carbon electrode,and the molecularly imprinted polymer（MIP）was modified on the surface of the CoS/ZnS composite material by electropolymerization.A molecularly imprinted electrochemical sensor for the rapid,sensitive,and highly selective detection of organochlorine pesticide chloroneb was obtained.Under the optimal conditions,the oxidation peak current density of chloroneb was linearly related to the concentration from 0.003 to 0.2μM and 0.2 to 3.2μM with a detection limit of 0.87 n M and a sensitivity of 52.27μA·μM^-1·cm^-2.The results show that the molecularly imprinted electrochemical sensor has good selectivity,stability,and repeatability,and has been successfully applied to detect chloroneb in licorice,cucumber,river water,and soil samples.（2）In the third chapter experiment,we calcined Zn-Co Prussian blue analogue（PBA）to obtain Zn O/Zn Co₂O₄ composite material,and use it as a substrate to synthesize Ni-Co layered double hydroxides（LDHs）on its surface.After calcination,hierarchical Ni Co₂O₄@Zn O/Zn Co₂O₄microspheres（MSs）were obtained.Ni Co₂O₄@Zn O/Zn Co₂O₄MSs not only have p-n hetero-junction characteristics,Ni Co₂O₄ and Zn Co₂O₄ are p-type semiconductors,and Zn O is n-type semiconductor,but also have a high specific surface area with a special structure,a structure in which a layered conductive network supports microspheres.When this material is used to modify the glassy carbon electrode,it significantly enhances the electrochemical sensing performance of pentachloronitrobenzene（PCNB）.Therefore,a new type of electrochemical sensor was constructed based on Ni Co₂O₄@Zn O/Zn Co₂O₄ MSs and molecularly imprinted polymer for the sensitive and highly selective detection of PCNB.Under the optimum conditions,the reduction peak current density of PCNB has a linear relationship with a concentration range of 0.05-5.5μM,the detection limit is 8.33 n M,and the sensitivity is 6.118μA?μM?1?cm?2.The MIP sensor proposed in this chapter has high selectivity,repeatability,and stability,and has been successfully used to detection PCNB residues in licorice,river water,and soil samples.（3）In the fourth chapter experiment,for the first time,we derived a composite of perovskite oxidesSr Co O₃ and Co₃O₄by calcining strontium ion-exchanged cobalt-based Prussian blue analogues.After modifying the carbon quantum dots（CQDs）,the catalytic activity of their peroxidase-like enzymes was explored.Among them,the doping ofSr Co O₃ and the modification of CQDs not only promote the generation of superoxide anion radicals（O₂^-·）and electron-hole pairs（h⁺）in the reaction system,but also accelerate the electron transfer between TMB and H₂O₂.Therefore,the peroxidase-like catalytic activity of the reaction system was significantly improved.We found that the complexation of tigecycline（TGC）and CQDs@Sr Co O₃/Co₃O₄ composite material enhanced the peroxidase-like catalytic activity of the reaction system,and established a molecularly imprinted sensor for detecting TGC.The sensor has a linear range of 0.02-6.0μM and a detection limit of 4.46 n M.It has been successfully applied to the detection of TGC in human serum and river water samples.（4）In the fifth chapter experiment,we derived Cu O/Co₃O₄ microspheres by calcining copper-cobalt Prussian blue analogues,and proved that they had peroxidase-like activity.Based on the catalytic oxidation activity of Cu O/Co₃O₄ composite material on TMB,combined with molecular imprinting technology,a colorimetric sensor for detecting fluconazole（FCZ）was constructed.When FCZ was combined with the imprinting site in the molecularly imprinted polymer,the catalytic area of the composite material was reduced,and the catalytic oxidation activity of the reaction system on TMB was inhibited,resulting in a decrease of the absorbance value of the oxidation product ox TMB in the ultraviolet spectrum.The difference in absorbance showed a linear relationship in the range of 0.8-8.6μM,and the detection limit was 171.3 n M.The prepared sensor also showed good selectivity and was successfully used to detect FCZ in human serum.