| Nanostructured arrays are widely used in the fields of optoelectronic devices and biosensors, and the structure parameters and the compositions of nanostructured arrays can have a significant impact on the performances of the device. Therefore, effective tailoring or doping of the nanostructured arrays is considered to be an important research direction for improving device performance.ZnO and TiO2nanostructures are ideal electrode materials for construction of the third-generation electrochemical biosensors, due to their biological compatibility, high specific surface area and activity, and non-toxic advantages. ZnO and TiO2nanostructured arrays directly formed on conductive substrates for working electrodes of electrochemical biosensors can make full use of the high specific surface area of nanostructure to immobilize redox protein, in addition to improving the working electrode stability and electronic transport properties.In this thesis, we focused on ZnO or TiO2micro/nanostructured arrays on conductive substrates, and performed a systematic research on preparation method, array structure tailoring, array-based electrochemical biosensing performance and etc. The main results are:The room-temperature nonequilibrium growth method was exploited by utilizing high alkaline growth solution. This method could control the growth direction of ZnO nanostructures and realize the room temperature preparation of ZnO nanosheets and nanorods arrays, variation in density and size as well as Sb incorporation was attempted. The supposed growth mechanisms are:in non-equilibrium state, high supersaturation can ensure the nucleation and growth processes of ZnO under room temperature. The excessive OHT is easily adsorbed on the positively charged (001)-Zn polar surface under the situation of Zn2+at certain concentration, which suppress the growth of the (001) surface and finally induces the nanosheet formation. On the other hand, when OH-increases to a certain degree, the saturated OH-will provide enough Zn(OH)42-units, a large number of Zn(OH)42will accelerate the oriented growth of ZnO. The promoting effect for the ZnO growth along c axis from OH-is significantly stronger than its shielding effect, resulting in the formation of nanorod structure. Therefore, one-or two-dimensional directed growth of ZnO nanostructures could be realized through the control of the concentration and ratio of Zn2+and OHT. Density changes of ZnO nanorod arrays obviously influence the electrowetting and field emission properties. The working electrode of H2O2biosensor based on ZnO nanosheets and nanorods arrays could realize the direct electron transfer between the enzyme and electrode, and the application of Sb incorporated ZnO nanosheets could improve the biosensing performance to some extent.Zero-dimensional Sb-doped ZnO microshperes array was successfully prepared by the carboxylate assisted hydrothermal method combined with heat treatment. The addition of carboxylates in the hydrothermal process, not only morphology was defined, but Sb ions involved in the formation of zinc-antimony-carboxylate complexes, leading to the homogeneous distribution of Sb in the complexes. Sb-doped ZnO microsphere arrays could be obtained after heat treatment. The electrode based on the Sb-doped ZnO microshperes array could improve the detection sensitivity of H2O2to271.2μA/mM·cm2, which is3times the sensitivity of the sensor based on undoped ZnO microspheres array.According to the high surface activity and high biocompatibility of TiO2nanostrucrures, we prepared TiO2nanodot arrays with different size and density on ITO substrate by spin-coating method. The results showed that the HRP adsorption ability of TiO2nanodots array on each plane area was enhanced with the increase of nanodot size. In addition, the TiO2nanodots array-based working electrode had the sensitivity up to1176μA/mM·cm2, with the linear detection range of1-780μM, also has good stability and repeatability. This can be attributed to the fact that the small gibbosities on the surface of TiO2nanodot and the strong electrostatic interaction could significantly shorten the electron tunneling distance between the active center of enzyme and the conductive site on the material, thus the electron transfer between the enzyme and the electrode is promoted.The working electrodes for H2O2and glucose electrochemical biosensors were fabricated based on TiO2nanorods array grown on a Ti substrates by hydrothermal method, and the immobilized enzymes were horseradish peroxidase, myoglobin and glucose oxidase, respectively. The H2O2biosensors made from horseradish peroxidase-immobilized electrodes showed an ultra-high sensitivity (4632μA/mM·cm) and an extremely low detection limits (0.012μM). The biosensor electrode fabricated in this research work showed great advantages compared with other H2O2electrochemical sensors based on TiO2nanostructures and one-dimensional nanostructured materials. The H2O2biosensor could keep high sensitivity and broaden the detection range at the same time after changing enzyme for myoglobin in electrode. TiO2nanorod arrays could also promote the direct electron transfer between glucose oxidase and electrode with a sensitivity to be43.3 μA/mM·cm2and the linear detection range of0.1-0.7mM. The superior performance of the present biosensors could be ascribed to the high aspect ratio and good conductivity of single crystal from nanorods, and excellent conductivity from metal substrates. |
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