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Biosensors 2018, 8(2), 34; https://doi.org/10.3390/bios8020034

Label-Free Electrochemical Immunoassay for C-Reactive Protein

Nanophotonics and Metrology Laboratory (NAM), Swiss Federal Institute of Technology Lausanne (EPFL), 1015 Lausanne, Switzerland
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Received: 7 March 2018 / Revised: 27 March 2018 / Accepted: 27 March 2018 / Published: 30 March 2018
(This article belongs to the Special Issue Immunoanalytical Tool with Electrochemical and Optical Detection)
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Abstract

C-reactive protein (CRP) is one of the most expressed proteins in blood during acute phase inflammation, and its minute level increase has also been recognized for the clinical diagnosis of cardio vascular diseases. Unfortunately, the available commercial immunoassays are labour intensive, require large sample volumes, and have practical limitations, such as low stability and high production costs. Hence, we have developed a simple, cost effective, and label-free electrochemical immunoassay for the measurement of CRP in a drop of serum sample using an immunosensor strip made up of a screen printed carbon electrode (SPE) modified with anti-CRP functionalized gold nanoparticles (AuNPs). The measurement relies on the decrease of the oxidation current of the redox indicator Fe3+/Fe2+, resulting from the immunoreaction between CRP and anti-CRP. Under optimal conditions, the present immunoassay measures CRP in a linear range from 0.4–200 nM (0.047–23.6 µg mL−1), with a detection limit of 0.15 nM (17 ng mL−1, S/N = 3) and sensitivity of 90.7 nA nM−1, in addition to a good reproducibility and storage stability. The analytical applicability of the presented immunoassay is verified by CRP measurements in human blood serum samples. This work provides the basis for a low-priced, safe, and easy-to-use point-of-care immunosensor assay to measure CRP at clinically relevant concentrations. View Full-Text
Keywords: screen printed electrode (SPE); C-reactive protein; electrochemical assay; label-free Immunosensor; gold nanoparticles screen printed electrode (SPE); C-reactive protein; electrochemical assay; label-free Immunosensor; gold nanoparticles
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).
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Thangamuthu, M.; Santschi, C.; J. F. Martin, O. Label-Free Electrochemical Immunoassay for C-Reactive Protein. Biosensors 2018, 8, 34.

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