Research On Enzyme-free Glucose Sensor Based On Nanomaterials

Diabetes is a chronic disease,its patients have been widely distributed around the world.In recent years,diabetes has become a common disease.Especially in low-income areas,due to inadequate medical treatment,the incidence of diabetes increased rapidly and generally.The initiation of diabetes is related to the amount of glucose in organisms.Whether for the control or prevention of diabetes,it is of vital importance for detection of blood glucose concentration in human body timely and accurately.Therefore,a low-cost sensor that can detect glucose level effectively and quickly has become the pivotal issue of current research.Existing electrochemical glucose sensors are divided into two categories,one is enzymatic glucose sensor,the other is enzyme-free glucose sensor.Although the enzyme glucose sensor has the characteristics of high sensitivity and selectivity,but enzymes are vulnerable to the environment（such as temperature,humidity,pH）and lose activity.The work of enzyme-free glucose sensor is mainly based on functional materials with electrocatalytic activity,the range of application of enzyme-free glucose sensor is broader than enzyme glucose sensor.There are many advantages such as low cost,fast response,high sensitivity and great anti-interference ability,also,the use of enzyme-free glucose sensor will not limited by oxygen content.In a word,as a promising alternative for existing glucose sensor,enzyme-free glucose sensor is widely concerned.The emergence of nanomaterials is nothing more than a great innovation of enzyme-free glucose sensitive materials.A wide variety of nanomaterials have emerged,and nanomaterials have been applied to various aspects of electrochemical enzyme-free glucose sensors to improve their electrochemical sensing performance.Carbon nanomaterials and metal nanomaterials are prominent particularly,the excellent electrical conductivity,chemical stability and biocompatibility make them become the first choice for the construction of various analytical structures.In this paper,the ultimate goal is to prepare the electrochemical enzyme-free glucose sensor,and to explore and discover new nanometer functional materials with glucose electrocatalytic activity,the synthesis of new carbon materials and metal materials with nanostructure was studied,and the prepared functional materials were applied to the electrochemical enzyme-free glucose sensor.The morphology characteristics and detection mechanisms of various prepared glucose sensitive materials were analyzed and summarized,and the performance of the enzyme-free glucose sensors were tested.Detailed works mainly include:（1）Simplified and improved the synthetic way of others,using the method of precipitation,copper chloride dihydrate and hydrofluoric acid were used as raw materials.In the research process,it was found that the microstructure of the Na₂CuF₄ could be changed by controlling the amount of copper chloride dihydrate,and the typical structure of Na₂CuF₄ with great sensing performance was obtained through the comparison of electrochemical sensing performance.The morphology of Na₂CuF₄ was characterized by SEM,and the chemical composition was verified by XRD and ICP tests.The electric catalytic properties of Na₂CuF₄ was analyzed by electrochemical characterization,proved that the prepared Na₂CuF₄/Au electrode has higher catalytic properties than bare gold,the detection limit of glucose sensor measured by experiment as 0.5μM,three sections of detection ranges were 0.01mM to0.15mM,0.15mM to 19.15mM,19.15mM to 63.15mM,corresponding sensitivities were229.68μA·mM^-1·cm^-2,62.8μA·mM^-1·cm^-2,235.54μA·mM^-1·cm^-2.The electrode has the advantages of high sensitivity,wide linear response range,great selectivity and stability,especially,high anti-interference ability to lactic acid in human body fluids.The synergistic effect of Na₂CuF₄ and gold electrode improved the comprehensive performance of the sensor greatly.（2）Au-CuO/BSA/MWCNTs composite material was synthesized using bovine serum albumin（BSA）template and used for the electrochemical detection of glucose in neutral environment.Au-CuO/BSA/MWCNTs modified gold electrode was constructed.BSA makes the composites fixed on the electrode surface very firmly and do not require the use of additional auxiliary materials for fixation.These characteristics brought by BSA are more suitable for commercial glucose sensor needs.The microstructure of the composites was characterized by SEM and TEM,and the electrocatalytic performance of the prepared Au-CuO/BSA/MWCNTs was characterized by electrochemical method.The detection limit of glucose sensor measured by experiment as 5μM,the detection ranges was 0.2mM to 8mM,sensitivities was 54.5μA·mM^-1·cm^-2.The electrode has moderate sensitivity and linear range,great selectivity and stability,which can be stored in the air for a long time,and can detect glucose under neutral conditions.（3）Au-oxSWCNHs composites were prepared by covalent bonding with cysteamine hydrochloride as intermediate,and were used to modified gold electrode.Electrochemical glucose sensor was constructed by three-electrode working system.The S-Au bond binding mode enables the gold nanoparticles to be dispersed uniformly and combined on the surface of SWCNH stably.SWCNH was modified with mixed acid and functional groups were introduced to provide a large number of chemically active binding sites for the material.The morphology of the composites was observed by SEM,raman spectroscopy was used to characterize the surface modification degree of oxSWCNH,which is the intensity ratio of the D-peak to the G-peak.Electrocatalytic performance of the prepared Au-oxSWCNHs was characterized by electrochemical method.The detection limit of glucose sensor measured by experiment as 0.72μM,two sections of detection ranges were 0.5mM to 2mM,4mM to12mM,corresponding sensitivities were 275.33μA·mM^-1·cm^-2,352.5μA·mM^-1·cm^-2.The electrode has high sensitivity,good selectivity,fast response and excellent comprehensive performance of glucose electrochemical detection.Au-oxSWCNHs/Au flexible electrodes were fabricated on gilded polyimide films by magnetron sputtering and photoetching process.