Application of magnetic core-shell microspheres on reagentless immunosensor based on direct electrochemistry of glucose oxidase for detection of carbohydrate antigen 19-9

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• 作者：Fangxin HuAuthor Vitae ; Shihong Chen ; ^{cshong@swu.edu.cn}Author Vitae ; Ruo Yuan ; ^{yuanruo@swu.edu.cn}Author Vitae
• 关键词：Magnetic core&ndash ; shell microspheres ; Multiwall carbon nanotubes ; CA19-9 ; Glucose oxidase ; Direct electron transfer ; Immunosensor
• 刊名：Sensors and Actuators B: Chemical
• 出版年：2013
• 出版时间：January, 2013
• 年：2013
• 卷：176
• 期：Complete
• 页码：713-722
• 全文大小：1460 K

文摘

This paper reported the production of magnetic core-shell composite microspheres (Fe₃O₄@SiO₂-Au@mSiO₂) which consist of a silica-protected magnetite particle core, an active gold nanoparticle transition layer and an outer mesoporous silica shell with pore channels. During the synthesis of the microspheres, the shape of the nanocomposite was changed from hexagons or quadrangles of Fe₃O₄ to well-defined spheres of Fe₃O₄@SiO₂-Au@mSiO₂. The synthesized microspheres were characterized by scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. A strategy was proposed for the fabrication of reagentless immunosensors based on direct electrochemistry of glucose oxidase (GOD), which employed multiwall carbon nanotubes and the prepared Fe₃O₄@SiO₂-Au@mSiO₂ as immobilization matrix. The immobilized GOD exhibited direct electrochemistry with a rate constant of 1.8 s^?1. The cyclic voltammetric (CV) and differential pulse voltammetric (DPV) peak currents of GOD decreased linearly with the increase of carbohydrate antigen 19-9 (CA19-9) concentrations from 0.01 to 1.11 U mL^?1 and 11.11 to 476.11 U mL^?1 with a relatively low detection limit of 0.004 U mL^?1. Furthermore, this strategy avoided the addition of electron transfer mediator, which simplified the immunoassay procedure and decreased the analytical time.