Use of immunomagnetic reduction for C-reactive protein assay in clinical samples

Chien-Hsi Chang,¹ Zhi-Xian Lai,¹ Hsiu-Li Lin,² Che-Chuan Yang,³ Hsin-Hsien Chen,^3,4 Shieh-Yueh Yang,⁵ Herng-Er Horng,³ Chin-Yih Hong,⁶ Hong-Chang Yang,⁴ Hsiu-Chen Lin<sup>1,7

1</sup>Department of Laboratory Medicine, Taipei Medical University Hospital, ²Department of Neurology, General Cathay Hospital, Sijhih Branch, ³Institute of Electro-optical Science and Technology, National Taiwan Normal University, ⁴Department of Physics, National Taiwan University, ⁵MagQu Co, Ltd, Sindian District, New Taipei City, ⁶Department of Mechanical Engineering, Nan-Kai University of Technology, Nan-tau County, ⁷Department of Pediatrics, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan

Background: Magnetic nanoparticles biofunctionalized with antibodies are able to recognize and bind to the corresponding antigens. In this work, anti-C-reactive protein (CRP) antibody was covalently conjugated onto the surface of magnetic nanoparticles to label CRP specifically in serum.
Methods: The level of serum CRP was detected by immunomagnetic reduction (IMR) assay, which identifies the changes in the magnetic signal representing the level of interaction between antibody-conjugated magnetic nanoparticles and CRP proteins. To investigate the feasibility of IMR for clinical application, pure CRP solutions and 40 human serum samples were tested for IMR detection of CRP to characterize sensitivity, specificity, and interference.
Results: In comparison with the immunoturbidimetry assay, the results of the IMR assay indicated higher sensitivity and had a high correlation with those of the current immunoturbidimetry assay.
Conclusion: We have developed a novel and promising way to assay CRP in human serum using immunomagnetic reduction in clinical diagnosis.

Keywords: magnetic nanoparticles, immunomagnetic reduction, C-reactive protein