The Study On The Construction Of Electrochemical Sensors For Glutathione And The Application In Food Detection

Glutathione(GSH),as an important tripeptide thiol in animals,is a commonly used indicator to characterize the antioxidant properties of meat,and it is often added as an additive to meat products to enhance flavor.Therefore,quantitative analysis of GSH in meat is of great significance for evaluating its nutritional value.So far,a variety of technologies for GSH qualification have been reported,like High-Performance Liquid Chromatography,Mass Spectrometry,Surface-Enhanced Raman Scattering,Capillary Electrophoresis.But these technologies have defects like expensive equipment,long analysis time,and complex detection operations.In contrast,electrochemical detection methods have the advantages of low cost,fast response,simple operation,and high sensitivity,and have been widely used in the fields of food and medical analysis.However,the complexity of pork components limits the application of conventional electrochemical methods in pork GSH detection.Therefore,in this study,two methods were used to construct the GSH electrochemical sensor,and the electrochemical performance of the sensor and its application potential in actual samples of pork and human serum were analyzed.In the first part of the research,a GSH electrochemical sensor was constructed based on the addition reaction between caffeic acid(CAF)derivatives and GSH.Firstly,2-dimensional nitrogen-doped ordered mesoporous carbon(2D-NOMC)was synthesized by the graphene template method and characterized by Transmission Electron Microscope(TEM),Atomic Force Microscope(AFM),Cyclic Voltammetry(CV),Electrochemical Impedance Spectroscopy(EIS),etc.It shows that the material exhibits the typical lamellar structure embedded with interconnected mesopores,and can significantly improve the conductivity of the electrode.Secondly,the electrochemical behavior of active materials(CAF,GSH,H~+,SH~-,etc.)was studied,and the results show that the redox of reaction products on the modified electrode is reversible one-electron/one-proton transfer process controlled by diffusion.Accordingly,a rational ECE reaction mechanism based on the 1,4-Michael addition reaction of o-quinone and mercapto is proposed,and verified by the product analysis in the electrolyte by High-Resolution Mass Spectrometry(HRMS).Lastly,based on the current response of the reaction product,a GSH electrochemical sensor was constructed and its electrochemical performance was analyzed.The fabricated electrochemical sensor exhibits a wide linear range of 5.0-6000.0?mol/L,a low limit of detection of 1.18?mol/L(S/N=3),decent reproducibility,and good selectivity.And the proposed method was further intended for the detection of GSH in pork and human serum samples with sensitive response and satisfactory recovery(97.30-107.30%).In the second part of the research,a GSH electrochemical sensor was constructed based on Au nanoparticles/acidified carbon nanotubes(Au NPs/A-CNTs)composite as catalysts.The Au NPs/A-CNTs was synthesized by photoreduction and characterized by TEM,X-Ray Diffraction(XRD),CV,EIS,etc.The Au NPs were found to be uniformly dispersed over the support,and the material shows good electrochemical catalytic performance.It is speculated that the material has a synergistic effect on the improvement of the electrocatalytic activity of GSH.By optimizing working parameters like material modification volume,electrolyte p H,scan rate,etc,the p H 7.0 and p H 2.0 GSH electrochemical sensors were constructed and the electrochemical performances were analyzed correspondingly.These two sensors have wide linear dynamic ranges of 0.5-5000.0?mol/L and 0.5-2000.0?mol/L with low limit of detection of 39.10 nmol/L and 25.59 nmol/L(S/N=3),respectively.Meanwhile,both electrochemical sensors present good reproducibility,selectivity,and stability.The p H 7.0 sensor was further expanded to GSH determination in pork samples with the recovery of 97.22-101.81%,and the p H 2.0 sensor was applied to GSH determination in human serum samples with the recovery of100.73-104.19%.These two sensors show excellent GSH electroanalysis performance.