Detection Of AFB1 And 6-BA By Electrochemical Immunosensor Based On Zn/Ni-ZIF-8-800

Food safety is closely related to human health,rapid and accurate testing technology is a prerequisite for ensuring food safety.At present,large-scale instrument detection methods such as high-performance liquid chromatography and liquid chromatography-mass spectrometry are mainly used for food safety detection.However,these methods have the disadvantages of time-consuming and labor-intensive,expensive instruments,requiring professional operation,and high detection cost.Electrochemical immunosensors are a new class of biosensors that combine specific immune reactions with highly sensitive sensing technology,and have higher sensitivity compared with traditional methods,it has a wide range of applications in medical,agricultural,food hygiene,environmental monitoring and other fields.Metal nanomaterials and carbon nanomaterials have the advantages of large specific surface area,excellent biocompatibility,and electrocatalytic activity.Introducing them into electrochemical immunosensors can increase the loading of biological macromolecules and improve sensor sensitivity.Based on this,this topic has constructed a series of highly sensitive electrochemical immunosensors based on metal nanomaterials and carbon nanomaterials as biological probes,aiming to provide researchers with a new theoretical basis and provide new insights for food safety testing detection method.The main research work is as follows:1、Preparation of Zn/Ni-ZIF-8-800@Graphene NanocompositesZn/Ni-ZIF-8 was synthesized by a simple solvothermal method.In order to remove the unreacted excess reactants,they were washed three times with methanol.After vacuum drying,it was placed in a tubular calcining furnace for calcination at high temperature for 1 hour,and ultrasonically composited with Graphene through a chitosan solution.The materials were preliminarily characterized by scanning electron microscope,X-ray diffractometer,X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy,and the proportion of complexes and the concentration of chitosan were optimized.The result is as follows:Zn/Ni-ZIF-8 is a monodisperse crystal state,and the morphology after calcination shrinks and deforms.From the changes of absorption peak s,it can be speculated that the possible changes of bonds are-NH stretching,imidazole ring stretching,-CH bending and-CH torsional vibration.At the same time,the organic ligands coordinate with the metal ions,and the synthesized products have high purity.The properties of the elements on the surface of Zn/Ni-ZIF-8-800 are similar to the electron binding energy comparison table and the results of the referenced literature,indicating that the Zn/Ni-ZIF-8-800 was initially synthesized successfully.The graphene has a typical wrinkled layered structure,and Zn/Ni-ZIF-8-800 was successfully attached to the graphene surface.Zn/Ni-ZIF-8-800: Graphene: Chitosan is 1:2:1,and the optimal working concentration of chitosan is 0.5 %.2、Establishment of a rapid electrochemical immunosensing method for the detection of aflatoxin B1 in peanut oilThe Zn/Ni-ZIF-8-800@Graphene composite was drop-coated on the surface of the bare glassy carbon electrode,and the gold nanoparticles were deposited on the surface of the composite modified electrode by potentiostatic deposition.The relationship between the rate and the current peak value is used to judge the nature of the reaction.The p H,gold deposition time,antibody concentration,antibody incubation time,and antigen-antibody reaction time were optimized.Characterization of the constructed electrochemical immunosensor.The result is as follows:The redox peak current increases with the scan rate,and the anodic peak current(Ipa)and cathodic peak current(Ipc)are linearly related to the square root of the scan rate.It indicates that the electrochemical reaction of AFB1 on this electrochemical immunosensor is a diffusion-controlled process.The optimal p H is p H 7.0,the optimal ratio of 1 % chloroauric acid and 0.5 M sulfuric acid is 1:20,the optimal deposition time of gold nanoparticles is 200 s,the optimal concentration of antibody is 16.5 μg/m L,and the optimal concentration of antibody is 1:20.The optimal incubation time is 40 min,and the optimal time for immune response is 40 min.Under the optimal conditions,the linear range of the electrochemical immunosensor is 0.01-100 ng/m L,the detection limit is 0.18 ng/m L,which is far lower than the national standard and the EU detection limit,and the recovery rate of standard addition is 80.26 %-109.60 % within the range.3、Establishment of an electrochemical immunosensing method for the rapid detection of 6-benzyl adenine in bean sproutsBy drop-coating the composite of inorganic metal framework and graphene onto the surface of the electrode,the electrode was electrochemically characterized after electrostatic deposition of nano-gold particles.The key factors affecting the experiment were optimized,and the standard curve of the target substance was established.The stability,reproducibility and specificity of the electrochemical immunosensor were analyzed.Finally,the practicability of the sensor was verified by the addition and recovery experiment.The result is as follows:The optimal deposition time of gold was 300 s,the optimal p H value was PH 6.0,the optimal concentration of antibody was 20 μg/m L,and the optimal time of immune reaction was 40 min.Under the optimal conditions,the linear range of the electrochemical immunosensor was 0.08-50 ng/m L,the detection limit was 0.24 ng/m L,and the spiked recovery was 90.9 %-105.0 %.