Characterization of Magnetic Markers and Sensors for Liquid-Phase Immunoassays Using Brownian Relaxation
Characterization of Magnetic Markers and Sensors for Liquid-Phase Immunoassays Using Brownian Relaxation
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DOI：
10.1109/tmag.2012.2194137
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发表时间：
2012-11-01
影响因子：
2.1
通讯作者：
Enpuku, Keiji
中科院分区：
文献类型：
--
作者：
Bhuiya, Anwarul Kabir;Asai, Masaki;Enpuku, Keiji
我们开发了一种利用磁标记物布朗弛豫的液相免疫分析技术。为了实现这一目标，我们首先对磁性标记物进行了表征，磁性标记物通常是磁性纳米颗粒的团聚体。分析了团聚体的磁性能，得到了布朗弛豫时间和尼尔弛豫时间以及磁矩等参数。利用这些关键参数，我们可以确定适合液相免疫分析的标记物。然后，我们进行了一种叫做生物素的生物靶标的检测。在本实验中，生物靶标被固定在几μ m大小的大聚合物珠的表面。结合和未结合（自由）标记是磁性区分的，不需要洗涤过程来分离它们。我们使用了三个磁传感器进行信号检测：一个SQUID，一个MR传感器和一个磁通门。据估计，SQUID、MR传感器和磁通门对分子数浓度的灵敏度分别高达5.6 × 10(-18) mol/ml、2.8 × 10(-16) mol/ml和2.8 × 10(-16) mol/ml。我们还证明了使用大磁矩的磁标记物可以提高灵敏度。
We have developed a liquid phase immunoassay technique using the Brownian relaxation of magnetic markers. In order to achieve this, we first characterized the magnetic markers, which are usually agglomerates of magnetic nanoparticles. The magnetic properties of the agglomerates were analyzed, and parameters such as the Brownian and Neel relaxation times and the magnetic moment were obtained. Using these key parameters, we could determine the markers that were suitable for the liquid-phase immunoassay. Then, we performed the detection of a biological target called biotin. In this experiment, biological targets were fixed on the surface of large polymer beads that were a few mu m in size. The bound and unbound (free) markers were magnetically distinguished without requiring a washing process to separate them. We used three magnetic sensors for the signal detection: a SQUID, an MR sensor, and a flux gate. The sensitivity of SQUID, MR sensor, and flux gate to the molecular-number concentration was estimated to be as high as 5.6 x 10(-18) mol/ml, 2.8 x 10(-16) mol/ml, and, 2.8 x 10(-16) mol/ml respectively. We also showed that the sensitivity could be improved by using magnetic markers with a large magnetic moment.