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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 Lin1,71Department 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, TaiwanBackground: 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

Kai-Wen Huang1, Shieh-Yueh Yang2,3, Yu-Wei Hong3, Jen-Jie Chieh3, Che-Chuan Yang3, Herng-Er Horng3, Chau-Chung Wu4, Chin-Yih Hong5, Hong-Chang Yang61Department of Surgery and Hepatitis Research Center, National Taiwan University Hospital, National Taiwan University, Taipei, 2MagQu Co, Ltd, Sindian Dist, New Taipei City, 3Institute of Electro-optical Science and Technology, National Taiwan Normal University, Taipei, 4Departments of Internal Medicine and Primary Care Medicine, College of Medicine, National Taiwan University, Taipei, 5Graduate Institute of Bio-medical Engineering, National Chung Hsing University, Taichung, 6Department of Physics, National Taiwan University, Taipei, TaiwanAbstract: Some previous reports have already shown the characterizations of immunomagnetic reduction (IMR). The assay technology involves the utilities of biofunctionalized magnetic nanoparticles to label target biomolecules. However, the detection threshold and interference tests for IMR have not been investigated in detail. In this study, alpha-fetoprotein (AFP) was used as a target biomolecule. The signals for AFP solutions of various concentrations, or with interfering materials, were detected via IMR. These samples were also used for characterizing the detection threshold and interference with enzyme-linked immunosorbent assay (ELISA). The results of assaying AFP level with IMR and ELISA were compared. The detection threshold for assaying AFP with IMR was found to be 3 ng/mL, which is 15 times lower than that of ELISA, and definitely suppresses false negative. For the interfering materials noted commonly in serum such as hemoglobin, bilirubin, triglyceride, and vascular endothelial growth factor, there was no detectable interfering effect when assaying AFP with IMR. Several serum samples from normal people and liver-tumor-bearing patients were used for the detections of AFP concentration via IMR. These results reveal the feasibilities of assaying AFP in blood using IMR, as well as achieving high-sensitive and high-specific assay for AFP.Keywords: immunomagnetic reduction, ELISA, biofunctionalized magnetic nanoparticles