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

• Published in: International journal of nanomedicine Vol. 9; no. Issue 1; pp. 5619 - 5626
• Main Authors: Cheng, Xianglin, Pu, Xu, Jun, Pen, Zhu, XiaoBo, Zhu, Di, Chen, Ming
• Format: Journal Article
• Language: English
• Published: New Zealand Dove Medical Press Limited 01.01.2014; Dove Press; Dove Medical Press
• Subjects: Adult; Aged; Aged, 80 and over; C-reactive protein; C-Reactive Protein - analysis; Female; fluorescence point-of-care test; Humans; immunochromatographic test; Immunochromatography - methods; Male; Measurement; Middle Aged; Original Research; Physiological aspects; Point-of-Care Systems; Quantum dots; Quantum Dots - chemistry; Young Adult; United States; China; quantum dots; immunochromatographic test; C-reactive protein; fluorescence point-of-care test
• ISSN: 1178-2013; 1176-9114; 1178-2013
• DOI: 10.2147/ijn.s74751

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. 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. 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). Our results demonstrated that the QD-based immunochromatographic test is a rapid, sensitive, accurate, and quantitative method for the detection of disease biomarkers.