Synthesis Of Metal Oxide Nanostructures And Its Electrochemical Sensing Glucose

The 21th century is the century of life science.With the powerful promotion of mobile internet,big data and artificial intelligence,the medical and health field which is based on modern life science,is undergoing unprecedented changes.Diabetes mellitus is a worldwide chronic disease.The detection,tracking and intervention of blood glucose concentration,especially at the early stage,are important to improve the live quality and life health of diabetes patients.Glucose biosensor,commonly known as the blood glucose meter,is a necessary tool for diabetes mellitus management in patients’daily life.Glucose biosensor can detect the blood glucose concentration with rapid response,high sensitivity and accuracy.Thus,from the perspective of the intervention and diagnosis,we can realize the prevention and implemente personalized tracking and monitoring of diabetes.In view of the detection requirements for high sensitivity,fast response,high stability,wide linear range of glucose biosensors,the purpose of this article is to solve the common problems of biological detection.This research concentrates on the preparation of new sensing nanomaterials,the structure regulation of three-dimensional micro-nano porous composite,the design of the semiconductor heterojunction,the integration research of the sensing material and the electrode,and so on.And,we expect to gain the key fabrication technology of high-performance glucose biosensor.The main research contents include the following aspects:1.The vertically cross-linked Bi₃Ti₂O₈F nanosheets were prepared by hydrothermal method with fluorine ion and pH value regulation.Due to the photoelectric catalysis of mimic peroxidase enzyme,the Bi₃Ti₂O₈F nanosheets immobilized Au electrode was implied for the colorimetric and electrochemical sensing of hydrogen peroxide.The unique structure of the cross-linked Bi₃Ti₂O₈F nanosheets provides abundant active sites for hydrogen peroxide adsorption and catalysis.Particularly,the layered intergrowth structure of[F–Bi–O–Bi–F]sheets can induce an internal electric field（IEF）,which greatly benefits to the separation of electron-hole pairs.The biosensor based on Bi₃Ti₂O₈F nanosheets has a high sensitivity of 1764μA·mM^-1·cm^-2,linear detection range of 1.43 to 1250μM and a rapid response time of1-2 s.The traditional titanium/bismuth-based semiconductor materials with rich micromorphology are applied to the biosensing field.The as-prepared colorimetric and electrochemical sensor exhibits the fast qualitative and accurate quantitative detection of hydrogen peroxide.2.Carbon materials gain popularity in biosensing area.However,it is difficult to immobilize biomaterials on graphene due to its smooth surface.Graphene quantum dots were cut away via the electrochemical redox method and porous three-dimensional graphene with a bandgap was generated due to the abundant defects and dangling bonds.The semiconducting graphene（SG）and substrate nickel metal is developed for fabricating a SG/Ni Schottky junction,which is the inner drives of accelerating charge transfer and thus resulting in significantly enhanced electrocatalytic effect.The 3D micro-nano porous graphene,with a larger specific surface area,more material/charge transfer and storage space.The micro-nano porous and more suspension bonds facilitate the transport,contact and reaction of the biological materials.The electrochemical performance towards H₂O₂ of the constructed 3D micro-nano porous graphene@nickel foam biosensor improves significantly,with the ultrahigh detection sensitivity of 4838μA·mM^-1·cm^-2,an ultralow detection limit of 20 nM and a linear detection range of 0.5to 1024μM.As a successful demonstration,the functionalized graphene with micro-nano pores shows the excellent electrochemical catalytic properties.3.An enzyme-based glucose electrochemical biosensor was fabricated by the glucose oxidase（GOx）immobilized p-NiO/n-Bi₄Ti₃O₁₂ sandwich heterojunction.Dandelion-like Bi₄Ti₃O₁₂ nanowires were directly grown on the titanium substrates by the hydrothermal method with the surfactant regulation.After the immobilization of glucose oxidase on the Bi₄Ti₃O₁₂ nanowires,a layer of NiO thin film was deposited by employing pulsed laser deposition at room temperature.Bi₄Ti₃O₁₂ nanowire spheres with larger specific surface areas,pores and folds,provide a suitable microenvironment for the large load of enzyme molecules.The constructed GOx/p-NiO/n-Bi₄Ti₃O₁₂sandwich structure effectively prevents the leakage of GOx.The p-NiO/n-Bi₄Ti₃O₁₂heterojunction facilitates the separation of electron-hole pairs,and its synergistic catalysis of the GOx leads to direct electrochemical sensing of the GOx/p-NiO/n-Bi₄Ti₃O₁₂ glucose sensor.The detection sensitivity of the enzyme-based glucose biosensor was 215μA·mM^-1·cm^-2,the detection limit was 1.26μM,and the linear detection range was 20 to 3550μM.The design and fabrication of semiconductor heterojunction enhance the redox interaction between enzyme and glucose,resulting in the outstanding detection performance of the biosensor.4.A facile and scalable in situ microelectrolysis nanofabrication technique was developed for preparing cross-linked Ni（OH）2 nanosheets on a novel three-dimensional porous nickel template with the pore diameter of 1-2μm.In the sintering process of the porous nickel framework formation,the porogen of NaCl induces a self-limiting surficial hot corrosion to claim the“start engine stop”mechanism.The self-limiting thermal corrosion effect activates the nickel surface and greatly accelerate the growth of Ni（OH）2.The integrated structure of 3D porous electrode and cross-linked nanosheets prevents the agglomeration or exfoliation of Ni（OH）2 nanosheets and offers abundant sites for the electrocatalysis of glucose,which improves the sensor stability and sensitivity significantly.The sensitivity of the enzyme-free glucose biosensor was2761.6μA·mM^-1·cm^-2,the detection limit was 0.46μM.The micro-electrolysis nanofabrication of metal hydroxide,without metal salts,acid and base,and the subsequent treatment,is a significant step forward in fabricating metal hydroxides based integrated electrodes.