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SQUID Microscope System for Biological Immunoassay

用于生物免疫分析的 SQUID 显微镜系统

基本信息

批准号：
12555117
负责人：
ENPUKU Keiji
金额：
$ 8.45万
依托单位：
Kyushu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

项目摘要

In this project, we have developed a SQUID microscope system for the application to biological immunoassay. In this system, an antibody is labeled with the so-called magnetic marker, and the binding reaction between antigen and its antibody is detected by measuring the magnetic signal from the marker. Utilizing a highly sensitive SQUID sensor that can measure very weak magnetic signal, we can detect very small binding reaction. Since the SQUID has to be cooled to T=77 K, we developed the SQUID microscope where the distance between the SQUID and the room temperature sample can be made less than 1 mm. We also developed a new marker using the Fe_3O_4 magnetic nanopartice with diameter of 25 nm. This marker can generate magnetic signal 10 times larger than the conventional marker with diameter of 10 nm. This marker can also keep the remanent magnetic field after the marker is magnetized with a large field. Using the SQUID microscope and the new marker, we can detect the marker as small as 1 pg. We also made an immunoassay experiment. For the antigen, we used the protein called IL8. At present, we can detect the IL8 as small as 1 pg. However, we can expect to detect the IL8 less than 0.1 pg from the noise performance of the system. Since the magnetic contamination of the substrate limits the detection level at present, we have to solve this problem in order to detect the IL8 of 0.1 pg.

在本计画中，我们发展了一套应用于生物免疫分析的SQUID显微系统。在该系统中，用所谓的磁性标记物标记抗体，并通过测量来自标记物的磁信号来检测抗原与其抗体之间的结合反应。利用高灵敏度的SQUID传感器，可以测量非常微弱的磁信号，我们可以检测到非常小的结合反应。由于SQUID必须冷却到T=77 K，我们研制了SQUID显微镜，使SQUID与室温样品之间的距离小于1 mm。我们还研制了一种新的标记器，使用直径为25 nm的Fe_3O_4磁性纳米颗粒。该标记物可以产生比直径为10 nm的常规标记物大10倍的磁信号。该标记物在用大磁场磁化后还可以保持剩余磁场。使用SQUID显微镜和新标记物，我们可以检测到小至1 pg的标记物。对于抗原，我们使用了称为IL 8的蛋白质。目前，我们可以检测到小至1 pg的IL 8。然而，从系统的噪声性能来看，我们可以期望检测到小于0.1 pg的IL 8。由于基质的磁性污染限制了目前的检测水平，我们必须解决这个问题，以便检测0.1 pg的IL 8。