Direct Electrochemistry of Horseradish Peroxidase at Nano Au/Zinc Oxide Cavities Microelectrode Array
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KeyWord:nano-Au  zinc oxide cavities array  microelectrode array  horseradish peroxidase  hydrogen peroxide
周宇,尹凡,孙磊,周丽娟 1.江苏大学化学化工学院,2.常熟理工学院江苏省新型功能材料重点建设实验室,3.苏州大学医学部药学院
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      A long range ordered nano Au/zinc oxide(ZnO) cavities array was fabricated on indium-tin oxide electrode surface by Langmuir-Blodgett technique and sol-gel technique.The morphology of this array was characterized by scanning electron microscopy.The cyclic voltammetric(CV) behavior of nano-Au/ZnO cavities array was in accordance with that of microelectrode,and the array can be used as microelectrodes array for biosensor design.A hydrogen peroxide(H2O2) biosensor was obtained by directly immobilizing horseradish peroxidase(HRP) into nano-Au modified ZnO cavities.Direct electrochemistry of HRP on nano-Au/ZnO cavities array was investigated.In pH 7.0 phosphate buffer,the CV curve of HRP/nano Au/ZnO cavities array electrode showed a pair of stable and quasi reversible redox peaks at-0.145 V and-0.230 V.The formal potential was about-0.188 V.The result indicated that the HRP immobilized in nano-Au/ ZnO cavities still retained good electrochemistry activity.The direct electron transfer rate constant was obtained to be 2.95 s-1.The hydrophilic ZnO surface and ordered cavities structure of ZnO cavities array provided not only the suitable microenvironment for HRP to retain its bioactivity/electrochemical activity,but also the large surface area for immobilization of HRP with high load.Meanwhile,the existance of nano gold particles also enhanced the electron transfer between HRP and the modified electrode.The prepared bio sensor provided an excellent electro catalysis activity for H2O2.The calibration curve was linear in the range of 667×10-6-1.31×10-3 mol/L for H2O2 concentration with a detection limit of 73×10-7 mol/L and the apparent Michaelis-Menten constant for HRP modified electrode was 0.411 mmol/L.