Preparation Of MOFs Fluorescence Probe And Its Application In Analysis And Detection

Fluorescence detection method can be effectively used for real-time monitoring and visual analysis of target analytes in the fields of environment and life,and has the characteristics of high accuracy,good sensitivity,strong selectivity and short response time.Luminescent metal-organic framework materials（LMOFs）have simple synthesis conditions,diverse structures,tunable fluorescence emission and stable pore structure,which are ideal materials for constructing fluorescence sensing platform.Two-dimensional LMOFs has large specific surface area and abundant active sites,which can be used not only as a sensitive fluorescent probe for detection of target analytes,but also as a carrier for loading other novel multifunctional nanomaterials（such as nanozymes）,supplementing the deficiency of the single material and further expanding the application of LMOFs in analysis and sensing.In this paper,based on the excellent properties of MOFs materials and the peroxidase-like activity of N-doped Mo S₂ nanoflowers,the fluorescence probe of MOFs composite materials was constructed and used for analysis and detection.The main research contents are as follows:（1）A simple and rapid fluorescent probe system was established with Zn-MOF,which realized the highly sensitive detection of tetracycline antibiotics and NH₄⁺in water.Zn-MOF was synthesized by one-step hydrothermal method with simple method and high yield.The prepared Zn-MOF has abundant pores,can exist stably in aqueous solution.When tetracycline antibiotics exist in Zn-MOF aqueous solution,based on the unique coordination between Zn and N,tetracycline antibiotics rich in N will be adsorbed into the pores of MOF,then aggregation induced emission will occur,which trigger the originally non-fluorescent Zn-MOF to produce fluorescence immediately.Based on this,we synthesized OTC@Zn-MOF fluorescent probe.NH₄⁺can replace the original ligand of Zn-MOF,which will disintegrate MOF and release OTC,resulting in decreased fluorescence.So,NH₄⁺can be detected.（2）Using NH₂-H₂BDC as organic ligand,NH₂-MIL-53（Al）fluorescent nanosheets were synthesized by one-step hydrothermal method for detecti ng F^-and Hg²⁺.The abundant pores of MOFs material can enrich the target,increase the reaction speed and amplify the fluorescence signal.The 2-dimensional sheet structure enables the material have larger specific surface area and more exposed active sites,which increases the effective contact between the material and the target analytes,and improves the sensitivity and accuracy of detection.The NH₂-MIL-53（Al）fluorescence probe was used to detect F^-and Hg²⁺in aqueous solution.F^-can form a largeπsystem with exposed-NH₂ of NH₂-MIL-53（Al）and H₂O molecules by hydrogen bonding,which enhances the fluorescence.However,Hg²⁺can obviously inhibit the fluorescence of NH₂-MIL-53（Al）,and the actual sample detection also proves that the fluorescent probe is also suitable for detecting target substances in environmental water samples.（3）The detection of total antioxidant capacity（TAC）plays an important role in evaluating the quality of antioxidant food and monitoring the level of huma n oxidative stress.N-doped Mo S₂ nano-flowers（N-Mo S₂NFs）with peroxidase-like activity were synthesized by solvothermal method.The doping of N element made Mo S₂ have rich defects and flower-like structure,which inhibited the accumulation of traditional Mo S₂ nanosheet and increased the effective specific surface area of Mo S₂.All of them increased the enzyme-like activity of Mo S₂.With TMB as substrate,TAC was detected by ultraviolet method.By mixing NH₂-MIL-53（Al）with N-Mo S₂NFs,N-Mo S₂NFs/NH₂-MIL-53（Al）nanocomposites were prepared.Using OPD（o-phenylenediamine）as substrate,based on the fluorescence resonance energy transfer between NH₂-MIL-53（Al）and ox-OPD（Oxidation of o-phenylenediamine）,the fluorescence detection of TAC is realized.