A label-free amperometric immunosensor based on horseradish peroxidase functionalized carbon nanotubes and bilayer gold nanoparticles |
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Authors: | Siming LiuAuthor VitaeRuo YuanAuthor Vitae Yaqin ChaiAuthor VitaeHuilan SuAuthor Vitae |
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Affiliation: | Education Ministry Key Laboratory on Luminescence and Real-Time Analysis, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, PR China |
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Abstract: | In this work, a novel label-free amperometric immunosensor has been constructed for detecting α-1-fetoprotein (AFP) based on nanocomposite of horseradish peroxidase (HRP) labeled carbon nanotubes (CNTs). First, the gold nanoparticles (AuNPs) were electrodeposited on the surface of the glass carbon electrode by electrochemical reduction of gold chloride tetrahydrate (HAuCl4) to immobilize horseradish peroxidase labeled carbon nanotubes (HRP-CNTs). Then HRP-CNTs bioconjugate was immobilized on the surface of the electrodeposited AuNPs layer by the combination of forces (coordination and electrostatic force). Subsequently, it was immersed into gold colloidal nanoparticles (GNPs) solution, which was used to immobilize antibody biomolecules (anti-AFP). Enhanced sensitivity was obtained by using bioconjugates featuring HRP labeled (HRP-CNTs), which had lager specific surface area and good electronic catalysis (current response signal) compared to carbon nanotubes. Under optimized conditions, the linear ranges were from 0.2 to 200 ng mL−1 with a detection limit of 0.067 ng mL−1 (at an S/N of 3). The proposed immunosenor showed good precision, acceptable stability and reproducibility and could be used for the detection AFP in normal human serum, which provided a potential alternative tool for the detection of protein in clinical diagnosis. |
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Keywords: | AFP, α-fetoprotein Anti-AFP, α-fetoprotein antibody HCC, hepatocellular carcinoma CNTs, carbon nanotubes MWCNTs, multiwalled carbon nanotubes HAuCl4, gold chloride tetrahydrate AuNPs, gold nanoparticles HRP, horseradish peroxidase GCE, glassy carbon electrode BSA, bovine serum albumin CV, cyclic voltammetry HAuCl4, gold chloride PBS, phosphate buffer saline SCE, saturated calomel reference electrode |
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