Biological immunoassay with high Tc superconducting quantum interference device (SQUID) magnetometer

Keiji Enpuku, Tadashi Minutant

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)


A high Tc superconducting quantum interference device (SQUID) magnetometer system is developed for the application to biological immunoassay. In this application, magnetic nanoparticles are used as magnetic markers to perform immunoassay, i.e., to detect binding reaction between an antigen and its antibody. The antibody is labeled with γ-Fe2O3 nanoparticles, and the binding reaction can be magnetically detected by measuring the magnetic field from the nanoparticles. Design and set up of the system is described, and the sensitivity of the system is studied in terms of detectable number of the magnetic markers. At present, we can detect 4×106 markers when the diameter of the marker is 50 nm. Total weight of the magnetic nanoparticles becomes 520 pg in this case. An experiment is also conducted to measure antigen-antibody reaction with the present system. It is shown that the sensitivity of the present system is 10 times better than that of the conventional method using an optical marker. A one order of magnitude improvement of sensitivity will be realized by the sophistication of the present system.

Original languageEnglish
Pages (from-to)43-48
Number of pages6
JournalIEICE Transactions on Electronics
Issue number1
Publication statusPublished - Jan 2001

All Science Journal Classification (ASJC) codes

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


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