The Design Of Fluorescence Sensor Based On MOFs And Detection Of Hydrogen Peroxide

Hydrogen peroxide（H₂O₂）is an important metabolite in organism,which plays an important role in cell differentiation and signal transduction.However,abnormal levels of H₂O₂will cause harm to cells and tissues,leading to a series of diseases,such as obesity and diabetes.Therefore,the development and construction of a simple,fast and accurate H₂O₂detection method is of great significance for the early diagnosis of diseases and human health.Among the numerous detection methods at present,the fluorescence sensor detection method based on the metal organic framework（MOFs）has the advantages of low cost,convenient operation and rapid response,which can be used for accurate,timely and highly sensitive detection of H₂O₂.Therefore,Cu-MOF,Cu/Fe-MOF and ZIF-8,three metal-organic frameworks,were used in this paper to construct a fluorescence sensor for detecting H₂O₂.First,Hemin doped Cu-hemin-MOF was synthesized by room temperature stirring method.Then,Cu/Fe-hemin-MOF with Cu²⁺and Fe³⁺bimetallic ion centers was synthesized.Finally,Zn-hemin-MOF with peroxide-like activity was synthesized by hydrothermal method.SEM,XRD,XPS and FT-IR were used to characterize the morphology,crystal structure,elemental composition and other physical and chemical properties of the prepared MOFs nanomaterials.The results showed that the prepared MOFs nanomaterials were successfully prepared.Three kinds of fluorescence sensing systems were constructed based on the peroxidase-like properties of the prepared MOFs,and their responses to H₂O₂were further discussed.Fluorescence spectrometer was used to study the performance of the three MOFS-type fluorescence sensors constructed,and finally it was applied to the detection of H₂O₂.Specific research contents are as follows:（1）Using Cu²⁺as metal center and Hemin as organic ligand,Cu-Hemin-MOF nanomaterials with peroxidase-like properties were synthesized in one step by stirring method at room temperature.Based on the principle of photoinduced electron transfer（PET）,a Cu-Hemin-MOF fluorescence sensor was constructed for the quantitative detection of H₂O₂.The factors affecting the performance of the sensor,such as the concentration of Cu-Hemin-MOF nanomaterials,OPD concentration,buffer p H and time,were optimized.Under the optimal experimental conditions,the response of the sensor is linear in the range of H₂O₂concentration from 15μM to 150μM.The actual detection limit is 15μM,and the theoretical detection limit is 5.3μM（S/N=3）.Moreover,the constructed Cu-Hemin-MOF fluorescence sensor has good selectivity in the detection of H₂O₂,and has achieved satisfactory results in the detection experiment of labeled recovery in actual serum samples.（2）The Cu/Fe-Hemin-MOF composite nanomaterials were prepared by one-step stirring method at room temperature with Cu²⁺and Fe³⁺as metal ion centers and Hemin as organic ligand.Based on the peroxidase-like properties of Cu/Fe-Hemin-MOF composite nanomaterials,a nanopoluminescence sensor was constructed and used for the fluorescence detection of H₂O₂.The experimental results show that the fluorescence sensor has a bilinear range in the detection of H₂O₂,and the linear range is:2.5-50μM and 0.05-0.5 m M.The correlation coefficients were R²=0.9943 and R²=0.99491,respectively.The actual detection limit was 2.5μM,and the theoretical detection limit was 0.92μM（S/N=3）.The Cu/Fe-hemin-MOF fluorescence sensor constructed by us has good selectivity in the detection of H₂O₂,and has been successfully used for the detection of H₂O₂in exosomes.（3）ZIF-8 nanomaterials were synthesized by one-step hydrothermal method with Zn²⁺as the metal ion center,2-methylimidazole and Hemin as the organic ligand.The particle size of the MOFs was about 100 nm.Based on the peroxidase-like activity of ZIF-8 nanomaterials,a Zn-Hemin-MOF fluorescence sensor was constructed and successfully used for the detection of H₂O₂.The linear range of H₂O₂detection is0.05-2.5μM（R²=0.99545）and 2.5-4.5μM（R²=0.99540）under the optimal experimental detection conditions.The actual detection limit is 0.05μM,and the theoretical detection limit is 0.016μM.In addition,the fluorescence sensor has been successfully used for the detection of intracellular H₂O₂.