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
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 singlewalled carbon nanotubes dispersed in chitosane functionalized with Lcysteine 2 Gold nanoparticles containing protein A and antialphafetoprotein antiAFP 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 goldconjugated 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 AuNPs 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 HRPNPs functionalized with hollow AuNPs 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 0025 to 50 ng mL−1 concentration range The detection limit for AFP is as low as 83 pg mL−1 We believe that this novel kind of immunoassay represents a promising tool for use in sensitive clinical assaysA 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 limitThis work was financially supported by NNSF of China 21075100 21275119 Ministry of Education of China Project 708073 Natural Science Foundation of Chongqing City CSTC2009BA1003 CSTC2011BA7003 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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