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Title of Journal: Microchim Acta

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Abbravation: Microchimica Acta

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Springer Vienna

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DOI

10.1016/0032-0633(75)90170-1

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1436-5073

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Horseradish peroxidase-loaded nanospheres attached to hollow gold nanoparticles as signal enhancers in an ultrasensitive immunoassay for alpha-fetoprotein

Authors: Ya Li, Ruo Yuan, Yaqin Chai, Ying Zhuo, Huilan Su, Yuxia Zhang,

Publish Date: 2014/02/04
Volume: 181, Issue:5-6, Pages: 679-685
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Abstract

We report on a novel electrochemical signal amplification strategy for use in immunoassays. The highly responsive immunoelectrode was constructed in the following way: (1) The surface of a gold electrode was covered with a layer single-walled carbon nanotubes dispersed in chitosane functionalized with L-cysteine; (2) Gold nanoparticles containing protein A and anti-alpha-fetoprotein (anti-AFP) were then covalently attached to the surface via the thiol groups of the chitosane. The electrode is then exposed to the analyte (AFP) which then is bound by the antibody. In the next step, a gold-conjugated secondary antibody is added that was prepared in the following way: (1) Horseradish peroxidase was crosslinked and the resulting spheres were coated with hollow gold nanoparticles (hollow Au-NPs) to give nanospheres of ~100 nm in diameter. (2) These were the coated with thionine and, in a last step, with secondary antibody. The use of these materials has several attractive features: The HRP-NPs functionalized with hollow Au-NPs possess a large surface area that can load the large amount of secondary antibody. Thionine (Thi) is highly redox active and improves the intensity of the signal. Carbon nanotubes were used because they possess an excellent electron transfer rate and large surface area. Following incubation of the modified electrode (a) with a sample containing AFP, (b) then with the secondary antibody, and (c) with washing buffer, the electrode is placed in a solution containing H2O2. The HRP in the smart secondary antibody causes the catalytic decomposition of H2O2 and the results in an electrical current that is linearly related to the concentration of AFP in the 0.025 to 5.0 ng mL−1 concentration range. The detection limit for AFP is as low as 8.3 pg mL−1. We believe that this novel kind of immunoassay represents a promising tool for use in sensitive clinical assays.A novel signal amplification strategy was presented, which is based on the attachment of hollow gold nanoparticles on the surface of immobilized horseradish peroxidase nanospheres. Its application to immunoassay displayed a wide linear response range with low detection limit.This work was financially supported by NNSF of China (21075100, 21275119), Ministry of Education of China (Project 708073), Natural Science Foundation of Chongqing City (CSTC-2009BA1003, CSTC-2011BA7003), Specialized Research Fund for Doctoral Program of Higher Education (20100182110015), State Key Laboratory of Electroanalytical Chemistry (SKLEAC 2010009), Fundamental Research Funds for the Central Universities (XDJK2012A004), China.


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Other Papers In This Journal:

  1. Horseradish peroxidase-loaded nanospheres attached to hollow gold nanoparticles as signal enhancers in an ultrasensitive immunoassay for alpha-fetoprotein
  2. A fluorescent chemical sensor for ethanol determination in alcoholic beverages
  3. Non-enzymatic sensing of glucose and hydrogen peroxide using a glassy carbon electrode modified with a nanocomposite consisting of nanoporous copper
  4. Dynamic evaluation of cell-secreted interferon gamma in response to drug stimulation via a sensitive electro-chemiluminescence immunosensor based on a glassy carbon electrode modified with graphene oxide
  5. Chemometrics to evaluate the quality of water sources for human consumption
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