Synthesis Of MOFs-based Photoelectrochemical Sensing Materials And Their Application In Antibiotic Detection

Since the discovery of antibiotics in the last century,humans have developed thousands of antibiotics,including hundreds of them in the fields of medicine,animal husbandry,and aquaculture,but at the same time,they have also caused serious abuses,which are harmful to human health and the ecological environment.For example,it can cause drug resistance in the human body,cause toxic damage to human organs,and even disrupt ecological balance,resulting in"super bacteria".Photoelectrochemical sensors,as a new analytical method with simple operation,fast analysis and high specificity,conform to the current development trend of detection technology.The PEC sensor combines the photoelectric conversion unit and the sensing recognition unit,so the determination of the analyte largely depends on the photoelectric conversion characteristics of the electrode material.In recent years,scientific researchers have devoted themselves to the design and development of photoactive materials with high photoelectric conversion efficiency and good stability.Metal-organic framework materials（MOFs）have become research hotspots due to the advantages of adjustable composition and structure,controllable properties,and functional design.This paper is devoted to designing MOFs-based photoactive materials,and modifying MOFs by means of functionalization of organic ligands,multi-stage sensitization of semiconductors,and hybridization of electron transport media.Chemical sensors enable sensitive detection of antibiotics in the environment.main tasks as follows:（1）MIL-68（In）-NH₂/MWCNT/CdS nanocomposite was prepared as a photoactive electrode by a two-step solvothermal method,and tetracycline（Tc）aptamer was used as sensor recognition unit to construct a label-free type PEC sensor.First,the modified amino group-modified MIL-68（In）（MIL-68（In）-NH₂）was dynamically transferred to the visible light region due to the introduction of the amino group into the organic ligand,which improved its visible light absorption capacity.Multi-walled carbon nanotubes（MWCNTs）as electron transport media promote the rapid transfer of electrons by adjusting the electron transport path.The formation of MIL-68（In）-NH₂/CdS heterojunctions significantly promotes transfer further improves the photoelectric conversion efficiency.The aptamer was then used to specifically capture the Tc molecule,and the concentration of Tc was monitored by observing the fluctuation of the photocurrent signal.Under optimized conditions,the PEC sensor shows a wide linear range of 0.1 nmol/Lμmol/L,and the detection limit is as low as 0.015 nmol/L.（2）A PEC aptamer sensor based on nitrogen-doped graphene quantum dots（N-GQDs）and AgBiS₂ co-sensitized Zn/Co bimetal oxide(Zn_xCo_3-x-x O₄)dodecahedron as photoactive electrodes was designed.For sensitive detection of ampicillin（AMP）residues in environmental media.The Zn_x Co_3-xO₄ dodecahedron derived from ZnCo-ZIF retains the unique hollow porous structure,which significantly improves the light utilization rate and shortens the photoelectron transmission path.N-GQDs with up-conversion luminescence performance and AgBiS₂ with optimal band gap for solar absorption were utilized to co-sensitized Zn_xCo_3-xO₄,maximize the use of visible light and further strengthen the PEC performance.Subsequently,the aptamer is combined with the photoactive electrode through chemical bonding.The PEC aptamer sensor has good photoelectric response performance to different concentrations of AMP,and the linear response range is 0.5 pmol/L-10 nmol/L,the detection limit is 0.25 pmol/L.（3）Firstly,cerium-doped UiO-66（Ce-UiO-66）was prepared by a solvothermal method.Ce-UiO-66 has Zr⁴⁺-Zr³⁺and Ce³⁺-Ce²⁺intervalence cycles,which can effectively improve charge separation efficiency.Subsequently,Ce-UiO-66 was further modified by[Ru（bpy）₃]²⁺and Mn:Bi₂S₃ co-sensitization to improve the photoelectric activity.On the one hand,[Ru（bpy）₃]²⁺can widen the absorption wavelength range,on the other hand,[Ru（bpy）₃]²⁺can react with the electron donor,maintain the photoelectric conversion process.Mn:Bi₂S₃ as a photosensitizer simultaneously formed[Ru（bpy）₃]²⁺@Ce-UiO-66/Mn:Bi₂S₃ heterostructure,which promoted the separation efficiency of electrons and holes to the greatest extent,and significantly improved photocurrent.The PEC sensor based on the photoactive electrode coupled aptamer constructed based on the above composite material realizes a sensitive detection of ofloxacin（OFL）with a detection range of 0.01 nmol/L-100 nmol/L and a limit detection as low as 6 pmol/L.By designing three MOFs-based photoactive materials,a series of photoelectrochemical aptamer sensors were constructed to detect antibiotics in the environment.The prepared sensor exhibits excellent performance and provides a new platform for constructing a new detection technique for environmental residual pollutants.