Construction Of Electrochemical Sensors For Glucose And Tetracycline Detection Based On Graphene Complex

Recently,graphene has become a research hotspot with its unique physical and chemical properties.Large specific surface area can provide more sites for loading nanoparticles,thus improve the catalytic activity of the composite material.Metal nanomaterials/graphene composites modified electrodes,combined with various electrochemical techniques,to build electrochemical sensors,was widely used.In this thesis,the first research part was focused on using PtNFs/GO to assemble GODx to fabricate a glucose biosensor.The second research part was using AuNPs/GO to load tetracycline MIP to construct tetracycline molecularly imprinted electrochemical sensor.The main contents are summarized as follows:In chapter 1,the development,basic principle and common system of ECL have been simply introduced;also,the basic principle,application of molecular imprinting was introduced.Here,we focused on the preparation,classification and application of molecular imprinting electrochemical sensor.In addition,the application of metal nanomaterials/graphene in electrochemical sensor was described.In chapter 2,a novel electrochemiluminescence?ECL?biosensor based on platinum nanoflowers?PtNFs?/graphene oxide?GO?/glucose oxidase?GODx?was constructed for glucose detection.PtNFs/GO was synthesized using a nontoxic,rapid,one-pot and template-free method,and was characterized by transmission electron microscopy?TEM?and high-resolution TEM techniques.The as-prepared PtNFs/GO with clean surface and multiporous structure was assembled with GODx to form a glucose biosensor.Based on ECL results,the PtNFs/GO/GODx film modified electrode displayed a high electrocatalytic activity towards the oxidation of glucose,which generated hydrogen peroxide?H₂O₂?to react with the luminol radicals,thus enhanced the luminol ECL.Under the optimized conditions,two linear regions of ECL intensity to glucose concentration were valid in the range from 5 to 80 ?mol L^-1?r = 0.9957?and 80 to 1000 ?mol L^-1?r = 0.9909?with a detection limit?S/N = 3?of 2.8 ?mol L^-1.In order to verify the reliability,the thus-fabricated biosensor was applied to determine the glucose concentration in glucose injection,glucose functional drink,and blood serum.The results indicated that the proposed biosensor presented good characteristics in terms of high sensitivity and good reproducibility for glucose determination,promising the applicability of this sensor in practical analysis.In chapter 3,tetracycline molecularly imprinted polymer was synthesized using thermal polymerization method and blended with AuNPs/GO and Nafion to modify the glassy carbon electrodes,thus constructed the tetracycline molecularly imprinted electrochemical sensor.TC was selectively enriched on the electrode surface by molecularly imprinted polymers.The electrochemical behavior of TC on the electrode was observed.The adsorption time and amount of modification was optimized.Under the optimized conditions,two linear regions of electrochemical intensity to TC concentration were valid in the range from 0.03?0.5 mg L^-1 and 0.5?20 mg L^-1 with the cyclic voltammetry?CV?method.Moreover,the differential pulse voltammetry?DPV?method was used to detect TC with low concentration.Our results showed that the linear range was from 1 to 30 ?gL^-1,and the detection limit was 0.7 ?g L^-1?S/N = 3?by DPV method.In order to verify the reliability,the thus-fabricated sensor was applied to determine TC in milk.The results indicated that the proposed sensor presented good characteristics in terms of high sensitivity and good reproducibility for TC determination,promising the applicability of this sensor in practical analysis.