An organic–inorganic hybrid nanostructure-functionalized electrode for electrochemical immunoassay of biomarker by using magnetic bionanolabels |
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Authors: | Biling Su Dianping Tang Juan Tang Qunfang Li Guonan Chen |
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Institution: | aMinistry of Education Key Laboratory of Analysis and Detection for Food Safety, Department of Chemistry, Fuzhou University, Fuzhou 350108, People’s Republic of China;bFujian Provincial Key Laboratory of Analysis and Detection Technology for Food Safety, Department of Chemistry, Fuzhou University, Fuzhou 350108, People’s Republic of China;cCollege of Pharmaceutical Sciences, Zunyi Medical College, Zunyi 563003, People’s Republic of China |
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Abstract: | A new electrochemical immunoassay of alpha-fetoprotein (AFP) was developed on an organic–inorganic hybrid nanostructure-functionalized carbon electrode by coupling with magnetic bionanolabels. Multi-walled carbon nanotubes (CNTs), single-stranded DNA, thionine and AFP were utilized for the construction of the immunosensor, while the core–shell Fe3O4-silver nanocomposites were employed for the label of horseradish peroxidase-anti-AFP conjugates (HRP-anti-AFP-AgFe). Electrochemical measurement toward AFP was carried out by using magnetic bionanolabels as traces and H2O2 as enzyme substrate with a competitive-type immunoassay mode. Experimental results indicated that the immunosensors with carbon nanotubes and DNA exhibited better electrochemical responses than those of without carbon nanotubes or DNA. Under optimal conditions, the electrochemical immunosensor by using HRP-anti-AFP-AgFe as signal antibodies exhibited a linear range of 0.001–200 ng mL−1 AFP with a low detection limit of 0.5 pg mL−1 at 3sB. Both intra- and inter-assay coefficients of variation were 7.3%, 9.4%, 8.7% and 10.2%, 7.8%, 9.4% toward 0.01, 30, 120 ng mL−1 AFP, respectively. The specificity and stability of the electrochemical immunoassay were acceptable. In addition, the methodology was validated for 12 clinical serum specimens including 9 positive specimens and 3 normal specimens, receiving a good correlation with the results obtained from the referenced electrochemiluminescence assay. |
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Keywords: | Alpha-fetoprotein Electrochemical immunoassay Organic&ndash inorganic hybrid composite electrode Magnetic bionanolabels |
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