Theranostics 2018; 8(12):3189-3197. doi:10.7150/thno.24034 This issue
1. Department of Chemistry, School of Physics and Chemistry, Gwangju Institute of Science and Technology (GIST), Gwangju 500-712, Republic of Korea
2. Department of Electrical Engineering, University of California, Los Angeles, California 90095, United States
3. Department of Physiology, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
4. Department of Emergency Medicine, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
*These authors contributed equally to this work.
The immunochromatographic (ICA) assay is a highly promising platform for rapid and simple detection of C-reactive protein (CRP) which is an indicator of the different phases of various diseases, as well as of inflammation and infection. However, the hook effect in the ICA assay limits the quantification of CRP levels at high CRP concentrations.
Methods: In this study, we developed a hook effect-free immunochromatographic assay (HEF-ICA) to detect CRP over a wide concentration range. The hook effect results from the simultaneous reaction of an excess target antigens with both immobilized and labeled antibodies respectively. To reduce the potential occurrence of this simultaneous reaction, we separated the migration of the target antigen and gold nanoparticle (AuNP)-labeled antibodies on a nitrocellulose membrane and analyzed the time profiles by modifying the ICA structure.
Results: The signal intensity of HEF-ICA was saturated at high CRP concentrations, without decreasing. The titration curve of HEF-ICA was adjusted with the Hill equation, and HEF-ICA was performed with the following parameters: limit of detection, 43 ng mL-1; dynamic range, 119 ng mL-1 to 100 µg mL-1. The accuracy of the newly developed assay was evaluated using 33 clinical samples via comparison with a clinical chemistry analyzer.
Conclusion: HEF-ICA enabled the measurement of a wide range of CRP concentrations without the hook effect, and was suitable for point-of-care testing with fingertip blood sampling, as only a minute sample volume (2.5 µL) was required.
Keywords: point-of-care testing, immunochromatographic assay, hook effect, C-reactive protein, wide range detection, minute sample volume