| Electrochemical sensor becomes a hot research field for researchers due to its high sensitivity,good selectivity and fast response time.The purpose of this paper is to prepare a molybdenite-based electrochemical sensor by using physical mixing of molybdenite and noble metal nanoparticles.The prepared sensor was used to the qualitative and quantitative determination of ascorbic acid?AA?,which is an important biological component.Since the biological components such as dopamine?DA?and uric acid?UA?are also present in human body,and these components and ascorbic acid are easily oxidized at the same voltage.The selective detection of AA is of great significance in real samples.In the process of glucose biosensor's construction,the immobilization method of glucose oxidase would affect the biosensor's performances such as sensitivity,selectivity,reproducibility,linear range,detection limit and lifetime,etc.In this study,a sensitive glucose biosensor was fabricated and the electrocatalytic activity of glucose oxidase on the modified electrode was also studied.This study would provide a new and high-valued applications for molybdenite.Molybdenite?MLN?and silver nanoparticles?Ag?are physically adsorbed on a glassy carbon electrode?GCE?to selectively detect ascorbic acid?AA?.The composites were characterized by scanning electron microscopy,high temperature confocal laser scanning microscopy,X-ray diffractometry,X-ray fluorescence analyzer and electrochemical methods.The prepared MLN/Ag-GCE sensor has good sensitivity,excellent reproducibility,good stability and selectivity.The detection range of AA is 3.0×10-5 M to 1.0×10-3 M.And the detection limit is 1.5×10-5 M.The synergy effect between molybdenite and Ag nanoparticles increases the electrocatalytic activity of the molybdenite based electrochemical sensor.Glucose biosensors have the advantages of accurate,simple,and fast response.They are often used to detect glucose concentration and have an irreplaceable role in clinical testing,fermentation control and food analysis.The wide range of applications has greatly promoted the development of glucose biosensor.The development and diversification make glucose sensor as one of the most researched and commercialized product in the world.In this study,the molybdenite?MLN?is used as the base material,and the glucose oxidase?GOD?is modified on the surface of the electrode to prepare the glucose sensor.In order to obtain a highly sensitive and selective electrochemical biosensor,the covalent binding method was used to immobilize glucose oxidase on the electrode by using glutaraldehyde?GA?as a coupling reagent,which further improved the stability of the sensor.The MLN,GA and GOD were immobilized on the surface of a clean glassy carbon electrode under optimal conditions to prepare a glucose electrochemical sensor.The steps of the electrode modification,adsorption time,concentration of each component,surface morphology of the electrode and p H value of the electrolyte solution were investigated and optimized.The electrodes were electrochemically characterized by scanning electron microscopy,cyclic voltammetry andelectrochemical methods.The optimum concentration of MLN is 40 mg/mL,the optimum immobilization time of molybdenite is 1 h,the concentration of glutaraldehyde?GA?is 10%,and the optimal immobilization time of GA is 1 h.The concentration of GOD is 1 mg/mL,the optimized immobilization time of GOD is 1 h,and the p H value of electrolyte is 5.5. |
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