Magnetic marker and high Tc superconducting quantum interference device for biological immunoassays

Keiji Enpuku, Katsuhiro Inoue, Kohji Yoshinaga, Akira Tsukamoto, Kazuo Saitoh, Keiji Tsukada, Akihiko Kandori, Yoshinori Sugiura, Shigenori Hamaoka, Hiroyuki Morita, Hiroyuki Kuma, Naotaka Hamasaki

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)


Magnetic immunoassays utilizing magnetic marker and high Tc superconducting quantum interference device (SQUID) have been performed. In this magnetic method, binding-reaction between an antigen and its antibody is detected by measuring the magnetic field from the magnetic marker. First, we discuss the magnetic property of the marker, and show that Fe3O 4 particles with diameter of 25 nm can be used for remanence measurement. We also show a design of the SQUID for sensitive detection of the magnetic signal from the marker. Next, we developed a measurement system utilizing the SQUID and a reaction chamber with very low magnetic contamination. Finally, we conducted an experiment on the detection of the biological materials called IL8 and IgE. At present, a few atto-mol of IL8 and IgE has been detected, which shows the high sensitivity of the present method.

Original languageEnglish
Pages (from-to)158-165
Number of pages8
JournalIEICE Transactions on Electronics
Issue number2
Publication statusPublished - Jan 1 2005
Externally publishedYes


  • High T SQUID
  • Immunoassay
  • Magnetic marker
  • Magnetic nanoparticle
  • Remanence

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering


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