Preparation And Biosensor Application Of Ordered TiO₂ Nanostructures

The determination of blood glucose is essential for the diagnosis and treatment of diabetes.Electrochemical biosensor combines electrochemical analysis with enzyme biotechnology and has been widely used in blood glucose testing.The bioelectrocatalytic activity of the sensing electrode is closely related to the carrier material.Among the various carrier materials,TiO2 nanomaterials have been widely used because of their high chemical stability,large specific surface area,low cost,good biocompatibility and and hydrophilicity,as well as controllable morphology,etc.TiO2 nanomaterials can be made into nanoparticles,1D nanorods,nano wires,nanotubes,2D nanosheets and other nanostructures.An ordered 1D nanoarray structure on the electrode is more conducive to the transport of electrons.Therefore,this paper chooses the ordered TiO2 nanorod arrays to modify the electrode of glucose electrochemical biosensor,and improve biosensor performance by optimizing the array structures.The main results include:1.TiO2 nanorod arrays(TiO2 NRs)were prepared on the FTO electrode by hydrothermal method,and further modified into branched TiO2 nanorod arrays(TiO2 BNRs)or TiO2 nanorod arrays with hollows on the top of nanrods(TiO2 NRs-HOT).The three kinds of prepared electrodes all presented electrochemical responses to glucose,which can be modified to fabricate sensing electrode with higher activity.2.The GOx was immobilized on the electrode surface by cross-linking method to prepare the enzyme-based glucose electrochemical sensor,and the sensing performance was analyzed based on the response current.The GOx/TiO2 NRs-HOT/FTO electrode show the best performance.The sensitivity reached 38.82?A mM-1cm-2,linear range was 0.001-0.1 mM(R2=0.9959),and detection limit of 0.77?M(S/N = 3).All of the enzyme-based sensors have a high selectivity to glucose and also have good stability and reproducibility.3.The CuO nanoparticles was deposited on the electrode surface by hydrothermal method to prepare enzyme-free glucose electrochemical sensor.Among all the enzyme-free sensors,CuO/TiO2 NRs-HOT/FTO electrode presented the highest sensitivity(875.41 ?A mM-1cm-2)with the linear range of 0.001-1mM(R2 = 0.9982).All of the enzyme-free sensors also have a high selectivity to glucose and good stability and reproducibility.4.The TiO2 NRs-HOT modified electrodes was subjected to high temperature treatment under ammonia atmosphere for nitrogen doping,and then GOx was linked to get GOx/N-TiO2 NRs-HOT/FTO enzyme electrode,while CuO nanopartilces was loaded to obtain CuO/N-TiO2-NRs-HOT/FTO electrode.The sensitivity of the enzyme-based sensor based on GOx/N-TiO2 NRs-HOT/FTO was increased to 160.98?A mM-1 cm-2,and the sensitivity of the enzyme-free sensor based on CuO/N-TiO2-NRs-HOT/FTO also increased to 1394.87 ?A mM-1 Cm-2.The result showed that a simple method of nitrogen doping could increase the conductivity of TiO2 nanorod arrays effectively and obviously improve the sensing performance of the sensors.