Preparation Of Copper-based Chemically Modified Electrode And Application For Glucose Sensing

Diabetes is a metabolic disease caused by defective or impaired function of insulin metabolism.The global patient population has exceeded 220 million and is expected to increase to 366 million by 2030,becoming one of the most concerning public health problems in the world.At present,the treatment plan of diabetes is to regularly monitor the blood glucose of diabetic patients,timely understand the glucose metabolism in the body,and adjust the treatment program in real time to achieve the best blood glucose level.It is of great significance for reducing the related disease and complications which develope a fast,sensitive and reliable glucose sensor to monitor blood glucose levels.It is notable that copper oxide?CuO?are good candidates for catalyzing glucose oxidation because of their excellent electrochemical activity,adjustable morphology and suitable surface charge properties.However,CuO is a semiconductor material,and its catalytic performance for glucose oxidation is easily limited by its electrical conductivity and morphology.Therefore,in this dissertation,CuO was used as the research object,and modified reduced graphene oxide?rGO?and carbon nanotubes?CNTs?with large specific surface area and excellent electrical conductivity were used to modify and prepare composite materials with different sizes and morphologies,which can be modification materials for non-enzymatic glucose sensor.And CuSO₄,Cu?NO₃?₂ or Cu?CH₃COO?₂ was used as the copper source to prepare CuO with three different morphological structures.The effect of copper salt precursors on the morphology of CuO and the effect of morphology on the detection performance were explored.The details are as follows:Rice-like CuO was synthesized with carbamide and copper nitrate by hydrothermal and in-situ decomposition methods.Any soft template and alkali were not used during the whole preparation process.The obtained CuO material was made into chemically modified electrode?CME?with Nafion solution for non-enzymatic glucose sensing.The results show that the obtained CuO particle looks like the rice grain.And its length and diameter are about0.5-1.0?m and 250-320 nm,respectively.The CME with 0.35 mg rice-like CuO sample have an obvious current response for glucose:the linear range is from 0.036 to 2.36 mmol/L,with a sensitivity of 950.36?A·L/?mmol·cm²?;and a detection limit of 0.065?mol/L?S/N=3?.It also exhibits a good anti-interference,stability and reliability for glucose.The conductivity of rice-like CuO was improved.The graphene oxide?GO?with layer structure was obtained by secondary exfoliation of graphite,and was used as a template agent to introduce the preparation process of rice-like CuO.A CuO/rGO nanocomposite material with excellent conductivity was obtained.The prepared nanocomposite material still maintains the outwardly oriented grain-like structure of CuO,and the particle size is reduced to nanoscale.The CME with the mass ratio of CuO to rGO is about 3.5:1,has an good current response for glucose.There is a good linear relationships in the concentration range of 0.01 to 2.53 mmol/L,with a high sensitivity of up to 1746.16?A·L/?mmol·cm²?;and a low detection limit of 0.047?mol/L?S/N=3?.It also exhibits a good reproducibility,anti-interference and reliability for glucose.The conductivity and catalytic activity of rice-like CuO were improved.Through the introduction of acidified CNTs,a CuO/CNTs composite material with synergistic effect was prepared.The prepared composites are spherical because of the template effect of CNTs.The interior of the sphere is arranged laminarly outward from the center of the sphere and still maintain the outwardly oriented CuO.The CNTs are connected between the CuO spheres and the nanoplatelets,so that the high-conductivity channels of the CNTs are connected with the CuO low-conductivity channels to form an electronic channel network and improve the electrical conductivity of the material.In addition,the incorporation of CNTs increased the catalytic site for glucose oxidation and produced a synergistic effect with CuO.When the mass of CNTs is 30%of the theoretical mass of CuO,the modified electrode composed of them has a strong current response ability to glucose.The linear range is from 0.20 to 4.56mmol/L,with a high sensitivity of up to 1377.01?A·L/?mmol·cm²?;and a low detection limit of 0.059?mol/L?S/N=3?.It also exhibits good anti-interference,reproducibility and stability for glucose.The morphology of CuO was improved.Using the method of condensation reflux and in-situ decomposition,CuSO₄,Cu?NO₃?₂ or Cu?CH₃COO?₂ was used as the copper source to prepare three kinds of nanostructure CuO.Due to the selective adsorption of different anions on different crystal faces,the prepared CuO exhibited three different morphology structures.Through electrochemical performance tests,it was found that nanorod-like CuO synthesized by CuSO₄ has a large specific surface area and multiple electron channels,and the unique gully structure prevents collapse of the structure during the application of pressure.Therefore,it showed the highest current response ability to glucose.There are two good linear relationships in the concentration range of 0.022 to 4.20 mmol/L,with high sensitivities of 4086.95?A·L/?mmol·cm²?and 2160.48?A·L/?mmol·cm²?,respectively;and low detection limit of 0.089?mol/L?S/N=3?.It also exhibits good reproducibility,anti-interference and stability for glucose.