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Rapid and quantitative detection of C-reactive protein using quantum dots and immunochromatographic test strips

Authors Cheng X, Pu X, Jun P, Zhu X, Zhu D, Chen M

Received 22 September 2014

Accepted for publication 1 November 2014

Published 2 December 2014 Volume 2014:9(1) Pages 5619—5626


Checked for plagiarism Yes

Review by Single-blind

Peer reviewer comments 3

Editor who approved publication: Prof. Dr. Thomas Webster

Xianglin Cheng,1,* Xu Pu,2,* Pen Jun,3 XiaoBo Zhu,3 Di Zhu,4 Ming Chen1

1Department of Laboratory Medicine, First Affiliated Hospital of Yangtze University, Jingzhou, 2Department of Laboratory Medicine, RenMin Hospital of Wuhan University, Wuhan, 3Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, Hubei, People’s Republic of China; 4Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA

*These authors contributed equally to this study and share first authorship

Background: Rapid immunochromatographic tests can detect disease markers in 10–15 minutes, which facilitates clinical diagnosis and treatment programs. However, most immunochromatographic tests employ gold nanoparticles as reporters, and these have only moderate sensitivity and act as qualitative methods for analyzing high biomarker concentrations.
Methods: In this study, we introduce quantum dots (QDs) as fluorescent probes and immunochromatographic strips to develop quantitative fluorescence point-of-care tests (QF-POCT) to analyze C-reactive protein (CRP) levels. Goat anti-rabbit IgG and rabbit IgG were used as control antibodies, and mouse monoclonal CRP antibody pairs were used for disease marker detection. One monoclonal CRP antibody was conjugated with QDs and served as a signal antibody, and the other monoclonal CRP antibody was dispensed onto the nitrocellulose membrane and served as a capturing antibody. In the presence of CRP, the fluorescence intensity of the monoclonal antibody-CRP-monoclonal antibody sandwich complex captured on the nitrocellulose membrane was determined using the fluorescence strip reader.
Results: QF-POCT assays could quantitatively analyze the concentration of CRP in 15 minutes had a detection limit of 0.25 mg/L, and had a wide detection linearity range (0.5–300 mg/L). The intra-assay and interassay coefficients of variation were 8.95% and 9.86% at 0.5 mg/L, 6.47% and 8.66% at 10 mg/L, and 6.81% and 9.10% at 60 mg/L, respectively. In a comparison between clinical samples, the results of this QD-based assay of CRP levels were significantly correlated with those of an Immulite 2000 assay (R=0.993, P<0.001).
Conclusion: Our results demonstrated that the QD-based immunochromatographic test is a rapid, sensitive, accurate, and quantitative method for the detection of disease biomarkers.

Keywords: C-reactive protein, immunochromatographic test, quantum dots, fluorescence point-of-care test

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