Liquid-Phase Detection of Biological Targets with Magnetic Marker and Superconducting Quantum Interference Device

Keiji ENPUKU  Yuki SUGIMOTO  Yuya TAMAI  Akira TSUKAMOTO  Takako MIZOGUCHI  Akihiko KANDORI  Naoki USUKI  Hisao KANZAKI  Kohji YOSHINAGA  Yoshinori SUGIURA  Hiroyuki KUMA  Naotaka HAMASAKI 

Publication
IEICE TRANSACTIONS on Electronics  Vol.E92-C  No.3  pp.315-322
Publication Date: 2009/03/01
Online ISSN: 1745-1353
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Recent Progress in Superconducting Analog Devices and Their Applications)
Category: INVITED
Keyword: 
liquid-phase immunoassay,  magnetic marker,  Brownian relaxation,  Neel relaxation,  B/F separation,  SQUID, 

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Summary: 
Liquid-phase detection of biological targets utilizing magnetic marker and superconducting quantum interference device (SQUID) magnetometer is shown. In this method, magnetic markers are coupled to the biological targets, and the binding reaction between them is detected by measuring the magnetic signal from the bound markers. Detection can be done in the liquid phase, i.e., we can detect only the bound markers even in the presence of unbound (free) markers. Since the detection principle is based on the different magnetic properties between the free and bound markers, we clarified the Brownian relaxation of the free markers and the Neel relaxation of the bound markers. Usefulness of the present method is demonstrated from the detection of the biological targets, such as biotin-coated polymer beads, IgE and Candida albicans.