| Microelectrode possessed of unexpected advantages comparing with a normal electrode, such as small capacitive-charging currents, reduced iR drop and steady-state diffusion currents, but the current response of a single microelectrode is too low, which need expensive instrument to detect it. Furthermore, if it has some problems, a false signal would be given, which may lead researchers to make an incorrect decision. Microelectrode array (MEA) is an assembly of microelectrodes in ordered manner. It can enlarge the current response because it can be thought as parallel connection of a large number of microelectrodes. Also, it can increase credibility of the microelectrode because general microelectrodes can provide coerrect response. Here, we prepared long-range ordered polystyrene (PS) particles monolayer by Langmuir-Blodgett (LB) technique and further was used as templates to construct nano-Au modified zinc oxide (ZnO) cavities microelectrodes array. Then we studied the direct electrochemistry of Hemoglobin (Hb) and Myoglobin (Mb) on these microelectrodes arrays. The work was as follows:1 Long-range ordered PS particles array was obtained by LB technique. The effects of experimental conditions on the quality of particle ordering, such as the subphase's composition (the volume ratio between doubly distilled deionized water and ethanol), the surface pressure and barriers speed was investigated. The results demonstrated that the size of ordered domain was up to a thousand square micron under optimum experimental conditions.2 Prepartion of ZnO cavities and nano-Au modified ZnO cavities microelectrodes array based on the templates of PS particles:(1) ZnO microcavities array was fabricated by electrodeposition of ZnO onto indium-doped tin oxide (ITO) electrode surface with ordered PS particles monolayer as template in the solution of Zn(SO4)2 and Zn(NO3)2 respectively. Morphologies of ZnO microcavities array were imaged by optical microscope and scanning electron microscopy. Electrochemical properties of ZnO microcavities array were characterized by cyclic voltammetry and electrochemistry impedance technique. The results showed that the structure of ZnO microcavities prepared in solution of Zn(SO4)2 was more compact comparing with Zn(NO3)2.(2) ZnO microcavities array was prepared by sol-gel technique. The effects of experimental conditions on the structure of microcavities, such as the concentration of sol-gel solution, times for vacuuming and heating rate during annealing were investigated. The optical property of ZnO was also studied.(3) Nano-Au modified ZnO microcavities array was constructed by electrodepositing gold onto ZnO microcavities. Scanning electron microscopy showed that nano-Au particles existed at the bottom of microcavities.3 Hb and Mb were immobilized on the nano-Au modified ZnO cavities microelectrodes array respectively. Direct electrochemistry of Hb and Mb were studied. The result indicated that the two biosensors provided excellent responses for H2O2. For Hb and Mb biosensors, linear relationships between current response and the concentration of H2O2 ranged from 3.3×10-5 to 1.1×10-2mol/L and 3.3×10-7 to 3.7×10-6 mol/L, detection limits were 4.1×10-6mol/L,8.9×10-8 mol/L, the reaction rate constants were calculated to be 0.389s-1 and 1.02s-1 respectively.
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