Preparation Of Functional Magnetic Nanomaterials And Its Application In Rapid Detection Of Vibrio Parahaemolyticus And Catechol

Magnetic nanomaterials(MNPs)is a new type of material which takes into account the advantages of nano materials and magnetic materials.MNPs are widely used in biomedicine,safety detection,aerospace,military,information technology and other fields.Because of its low price,easy access to raw materials and easy mass production,it is considered as one of the most"promising"materials.Rapid detection technology has the characteristics of fast detection speed and low cost,which has a broad application prospect in the quality and safety supervision of aquatic products.In this study,three new functional MNPs were developed and applied to the rapid detection of Vibrio parahaematolyticus(VP)and catechol(CC)in aquatic products or cultured water.Through the development and preparation of new MNPs,the rapid detection method of VP in aquatic products was established by using DNA magnetic extraction and PCR technology,which provided a new idea for rapid screening of VP;By modifying MNPs and combining them with micro array interdigital electrode,two new high-sensitivity sensors,magnetic noble metal biosensor and magnetic MOF biomimetic biosensor,were constructed,which realized the high-sensitivity detection of CC residues in aquaculture water environment,and provided a new solution for improving aquaculture water environment.The research contents and results are as follows:(1)In this study,a preparation method of iron-based MNPs was developed.Magnetic nano-Fe₃O₄ was prepared by this method,and functional MNPs were developed based on the preparation of magnetic nano-Fe₃O₄.Magnetic Fe₃O₄ nanoparticles were prepared by alkaline coprecipitation method.The effects of different alkali sources and different solvent ratios on the products were studied.The results show that:Magnetic Fe₃O₄nanoparticles with uniform morphology were prepared in the reaction system of 2:1 ratio of Fe³⁺to Fe²⁺and 1:1 ratio of ethanol to water.The particle size was about 15 nm and the saturation magnetization was about 47.27 emu·g^-1.The rapid preparation method of magnetic nano-Fe₃O₄ established in this study laid a solid foundation for the follow-up research on the functionalization of MNPs.(2)By studying the rapid DNA extraction method of silicon functionalized Fe₃O₄@Si O₂,a DNA magnetic extraction platform was established,Through the combination of DNA magnetic extraction and PCR technology,the rapid screening of VP in aquatic products was realized.The effects of morphology and structure of Fe₃O₄@Si O₂ and DNA extraction system on the efficiency of DNA magnetic extraction were studied.Under the best experimental conditions,we carried out VP screening for oyster and other aquatic products The results show that:When the p H of extraction system was 5.0,the particle size of Fe₃O₄@Si O₂ was 105.89 nm,and the thickness of silica layer was 25 nm,the magnetic extraction efficiency of DNA was the highest.Under these conditions,the surface of a is smooth,the dispersion is good,and the saturation magnetization is 17.58 emu·g^-1.Under the action of magnetic field,DNA and impurities can be separated in 10 s,and the extraction rate of DNA is as high as 80%;92 samples of aquatic products were detected by DNA magnetic extraction and PCR,and 17 positive samples were detected.Compared with VP national standard(GB4789.7-2013),the detection time was shortened from one week to 6 hours,which greatly improved the detection efficiency of VP.(3)A magnetic precious metal biological enzyme sensor was constructed,which used Tyrosinase(tyr)as the recognition module,precious metal modified MNPs(Fe₃O₄@PVP@Au)as the sensitization module,interdigital electrode as carrier,and electrochemical workstation as the detection system.The sensor realized the rapid detection of CC residue in aquaculture water.The preparation method and internal structure of interdigital electrode and Fe₃O₄@PVP@Au were studied.The effects of gold nanoparticles and magnetic field height on sensor sensitivity were verified.The working stability of the sensor is studied.The results showed that:The magnetic field improves the sensitivity of the sensor by changing the arrangement of Fe₃O₄@PVP@Au on the surface of interdigital electrode;The magnetic field improves the sensitivity of the sensor by changing the arrangement of Fe₃O₄@PVP@Au on the surface of interdigital electrode;Under the optimum magnetic field height(250?m),the sensitivity of the sensor is increased by 23 times;Under this condition,the water samples were detected,The linear range of the sensor is 5?100?mol·L^-1,and the minimum detection limit is 44.6 nmol·L^-1.At the same time,the sensor has good reproducibility and can be tested 50 times repeatedly The magnetic precious metal biosensor has the advantages of low detection limit,short detection time and good reproducibility,which can realize the rapid detection of CC residues in aquaculture water and provide strong support for aquaculture and other water detection..(4)This study built a magnetic MOF biomimetic enzyme sensor with magnetic biomimetic enzyme as recognition and sensitization module,interdigital electrode as carrier and electrochemical workstation as detection system.The sensor can be used to detect CC residue in aquaculture water.This experiment studied the preparation method and internal structure of magnetic MOF biomimetic enzyme,verified the recognition performance of MOF biomimetic enzyme,explored the sensitization mechanism of magnetic MOF biomimetic enzyme,and completed the detection of spiked aquaculture water samples under the optimal parameters of the sensor.The results showed that:In this study,magnetic MOF biomimetic enzyme which can catalyze the oxidation of CC was successfully prepared;MOF can increase signal intensity by 15 times by providing electron transfer channel on interdigital electrode surface;By changing the distribution of magnetic MOF on the surface of interdigital electrode,the signal intensity is increased by 10 times.Under the optimal parameters of the sensor,the water samples were detected,The linear range of the sensor is 10?50?mol·L^-1,and the detection limit is 74.4 nmol·L^-1,At the same time,the sensor has good stability,and the detection sensitivity will not decrease in 21 days.The biosensor overcomes the problem of enzyme inactivation and is more suitable for the rapid detection of CC.