The Copper And Iron-based Metal-organic Framewoks As Enzyme-mimics And Their Analytical Applications

Nanozymes is a kind of nanomaterial with enzyme-mimic properties,owning the advantages of high activity,high stability,low cost and easy preparation.Nanozymes overcome the inherent limitations of easy inactivation,storage difficulties and high cost of natural enzymes,and are used as substitutes of natural enzymes in the fields of biosensors,environmental governance and medicine.Based on the structure and composition of nanozymes,they can be simply divided into metal-organic materials（including metal and metal oxide nanoparticles,metal-organic porous nanomaterials）and inorganic materials（carbon-based nanomaterials）.Among them,the metal-organic frameworks（MOFs）based nanozymes own not only the structural characteristics of large specific surface area,porosity and abundant metal active sites,but also the excellent optical,electrical and stimulus response properties.In addition,due to the modular construction feature of MOFs,single-component MOFs with different enzyme-like properties can be obtained by rationally designing building blocks,which greatly enriches the types of nanozymes and has the great potential to tailor their performance.Based on that,with transition metals copper and iron as metal modules,we synthesized copper and iron-based MOFs and their enzyme-like properties and mechanisms were studied.In the end,these MOFs were applied for the detection of drug molecule,the degradation of fluorine-containing drugs,and mimicking the metabolism of drugs.This thesis includes three parts as follows:1.Copper-based metal-organic frameworks as peroxide-mimics for the determination of quercetin.The fibrous Cu-based metal-organic gels（Cu-MOGs）were simply mixed by organic ligands 1,3,5-（4-carboxyphenyl）benzene and Cu²⁺at room temperature.The flower-like Cu-MOFs were obtained by the mixed solvent method using Cu-MOGs as precursors.The Cu-MOFs possessed excellent peroxidase-like activity,which could catalyze the continuous decomposition of H₂O₂ and dissolved oxygen to generate reactive oxygen species（ROS）,thereby oxidizing luminol to produce continuous chemiluminescence（CL）.Since quercetin could compete ROS with luminol to inhibit the continuous CL,a new CL method for detecting quercetin has been established.Under the optimal conditions,the concentration of quercetin had a good linear relationship with the CL intensity,and the linear range and detection limit were 0.05μM-1.2μmol/L and 49.7nmol/L,respectively.2.Iron-based metal-organic frameworks as photo-enhanced peroxide-mimics for the degradation of ciprofloxacin.Four rod-shaped Fe-MOFs（named Fe-TCPP-1,Fe-TCPP-2,Fe-TCPP-3 and Fe-TCPP-4）with different aspect ratios were synthesized by microwave method,using meso-Tetrakis（4-carboxyphenyl）porphyrin（H₂TCPP）as the organic ligands,Fe³⁺as the metal nodes and benzoic acid as regulator.The rod-like Fe-MOFs possessed high photo-enhanced peroxidase-like activity.Among them,Fe-TCPP-3 showed the largest pore structure and good photochemical activity,thus Fe-TCPP-3showed excellent photo-enhanced peroxide-like activity.With photo irradiation,the photo-generated electrons of TCPP ligands in Fe-MOFs would transfer to the metal nodes Fe³⁺by intermolecular electron transfer to reduce Fe³⁺into Fe²⁺,catalyzing H₂O₂decompose into strong oxidizing OH˙to further oxidize substrates into small molecules.Therefore,Fe-TCPP-3 was applied to degrade ciprofloxacin.3.Bimetallic organic frameworks as multienzyme-mimics for the metabolism of1,4-dihydropyridine.The bimetallic organic frameworks（FePCN）with spindles morphology were synthesized by hydrothermal method,using Fe（III）meso-Tetra（4-carboxyphenyl）porphine chloride as the organic ligands and Zr⁴⁺as the metal nodes,respectively.The spindle-like FePCN exhibited excellent multienzyme-like activities,namely oxidase-（OXD-like）,peroxidase-（POD-like）and phosphatase-like（POP-like）activities.The iron centers in FePCN were the active centers of POD-like and OXD-like properties,and the Zr-O clusters were served as the POP-like active centers.Based on the high OXD-like activity,FePCN could catalyze dissolved oxygen decompose into ROS to mimic the activity of CYP3A4,one of cytochrome P450 subtypes,and was used to simulate the metabolism process of 1,4-dihydropyridine which was catalyzed by CYP3A4.Based on the high POD-like activity,FePCN could catalyze H₂O₂ decompose into ROS to further oxidized TMB under neutral conditions,and the analytical method for detecting H₂O₂ under neutral conditions was established.Based on the high POP-like property,FePCN could catalyze ATP dephosphorylate into adenosine.