Magnetic Sensor Based Liquid-Phase Immunoassays for the Detection of Biological Targets

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We have developed a liquid-phase immunoassay technique for the detection of biological targets using magnetic markers. In this method, Brownian relaxation of magnetic markers in solution was used to perform the liquid-phase detection. Biological targets were fixed on the surface of large polymer beads whose size was typically a few 1m. When the magnetic markers were bound to the targets, their Brownian relaxation time was dominated by that of the polymer bead, becoming much longer than that of unbound (free) markers. The resulting difference between the magnetic properties of the bound and free markers was detected by relaxation measurements. Therefore, we can magnetically distinguish between the bound and free markers, i.e., we can omit a time consuming washing process called bound/free separation. We developed a detection system using magneto-resistive (MR) and flux gate sensors. We could detect 1.4 × 107 and 8.3 × 106 bound markers in 60 1l of solution for the cases of MR and flux gate sensors, respectively. If we assume that a single marker is bound to a single target, this sensitivity can be expressed as 3.8 × 10-16 mol/ml and 2.3×10-16 mol/ml in terms of the molecular-number concentration. We also demonstrated the detection of biological targets called biotins, which were conjugated on the surface of the polystyrene beads with a diameter of 3.3 1m. A strong relationship was obtained between the number of bound markers and the number of biotin-conjugated polymer beads, which confirmed the validity of the present method.

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詳細情報 詳細情報について

  • CRID
    1390290699813870208
  • NII論文ID
    120003370629
  • NII書誌ID
    AN10569524
  • DOI
    10.15017/20052
  • ISSN
    21880891
    13423819
  • HANDLE
    2324/20052
  • 本文言語コード
    en
  • データソース種別
    • JaLC
    • IRDB
    • CiNii Articles
  • 抄録ライセンスフラグ
    使用可

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