Research On Disease Markers And Mycotoxin Biosensing Platform Based On Metal-Organic Frame Materials And Nanoenzymes

Metal organic framework materials（MOFs）are porous nanomaterials with high specific surface area and tunable pores.Simple synthesis,high catalytic properties,high stability and low cost are all significant advantages of nanoenzymes.Both types of materials are heavily used in the field of biosensing and have good potential for application.In this thesis,metal-organic framework materials Ui O-66-NH₂（Zr-MOF-NH₂）,MIL-125-NH₂（Ti-MOF-NH₂）;Ni₃V₂O₈ and Fe/Eu-MOF materials with mimic enzyme properties were synthesized and used in sensing systems for the detection of disease markers and mycotoxin.This thesis is constructed specifically in the following four working sections:（1）The experiment constructed a dual signal detection for ascorbic acid（AA）sensing system based on UV absorption and chromaticity of the test strip.This sensing system oxidizes 3,3’,5,5’-tetramethylbiphenylamine（TMB）to blue oxide TMB（ox TMB）based on the analog peroxidase activity of Ni₃V₂O₈.The ox TMB shows a distinct absorption peak at 652 nm.AA reduces the blue ox TMB to the colourless TMB,and quantitative detection of AA is possible by detecting the decrease of absorption peak intensity by an UV-visible spectrophotometer.Under optimal experimental conditions,the sensing system showed good selectivity with a low AA detection limit of 0.032μmol/L.This sensing system can be used for the detection of AA in actual juices and beverages sample,and has better application prospects.Meanwhile,the experiment also constructed a test strip method for detecting AA,which provides a new strategy for rapid,efficient and sensitive ascorbic acid detection.（2）RGB refers to a mathematically specific expression of a colour set and can be understood as assigning an RGB intensity value in the range 0 to 255 to an image.Nowadays,more and more colorimetric reactions combined with RGB have become a research hotspot.A three-mode sensing system for the detection of cholesterol with high sensitivity based on Fe/Eu-MOF was designed.Through the catalysis of cholesterol oxidase,cholesterol produces hydrogen peroxide.After adding Fe/Eu-MOF material,TMB color changes from colorless to blue（ox TMB）,so that cholesterol is detected by ultraviolet spectrophotometer and smartphones through RGB values.ox TMB can quench the fluorescence signal of Fe/Eu-MOF.Cholesterol can also be detected according to the fluorescence intensity.Therefore,a three-mode cholesterol detection sensing system was constructed.The advantages of higher sensitivity,shorter test time,wider linear range and better selectivity are all available with this sensing system.The sensing system can detect cholesterol in real serum,adding a new way to the detection of cholesterol.（3）The specific recognition of aflatoxin B₁（AFB₁）with AFB₁ aptamers was used to determine the content of AFB₁.Au NPs@Ui O-66-NH₂,a metal-organic framework loaded with Au NPs,was used as a signal probe.The AFB₁ aptamer labeled with Au NPs@Ui O-66-NH₂ was bound to T chain through hybridization.Experimental DPV response currents of Au NPs@Ui O-66-NH₂ composites were determined by the DPV method in Tris-HCl buffer solution,and a signal-off electrochemical aptasensor was constructed.The sensor showed a linear correlation between 0.1 and 110 ng/m L for AFB₁ with a low detection limit of 0.033 ng/m L and a linear equation ofΔI=0.5487x+0.9530,which realizes the quantitative detection of the target.This work provides a new method for the trace detection of AFB₁.（4）The construction of network DNA is attracting attention.A network DNA（Multi-Thi network DNA）with Thi-modified Pt Ni NCs@MIL-125-NH₂as a node for sensitive detection of white locytokine-6（IL-6）was designed.Thi-modified Pt Ni NCs@MIL-125-NH₂ was used as the signal label to construct a signal amplified electrochemical biosensor.Compared to other signal amplification strategies,this aptamsensor does not require additional substrates.Moreover,the designed multi-Thi network DNA can load more Thi@Pt Ni NCs@MIL-125-NH₂ signal tags for amplifying the signal.The aptamsensor has a good electrochemical response to IL-6.Linear response of IL-6 content between 1 and 10000 pg/m L.Correlation coefficient R²=0.9917.The detection limit is 0.89 pg/m L.The experimentally constructed sensor not only amplifies the signal,but also has the advantages of high sensitivity and simplicity of operation.