Ultrasensitive magnetic biosensor for homogeneous immunoassay
Ultrasensitive magnetic biosensor for homogeneous immunoassay
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DOI：
10.1073/pnas.97.26.14268
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发表时间：
2000-12-19
影响因子：
11.1
通讯作者：
Clarke, J
中科院分区：
文献类型：
--
作者：
Chemla, YR;Crossman, HL;Clarke, J
描述了一种利用超顺磁性纳米颗粒和基于高温超导量子干涉装置(SQUID)的“显微镜”对生物目标进行特定、灵敏、定量和快速检测的技术。在这项技术中，将与靶结合在一起的聚乳酸薄膜放置在显微镜上。在室温和大气压下，该公司与鱿鱼的距离通常为40微米，而鱿鱼在真空中的温度为77K。将携带针对目标的抗体的磁性纳米颗粒悬浮液加入井中的混合物中，并将1-S脉冲磁场平行施加到鱿鱼身上。在这个对准磁场的存在下，纳米颗粒会产生净磁化，当磁场关闭时，净磁化会松弛。未结合的纳米粒子通过布朗旋转迅速松弛，并且没有提供可测量的信号。附着在薄膜上目标的纳米颗粒被固定并经历尼尔松弛，产生缓慢衰减的磁通量，被鱿鱼检测到。区分结合和非结合标记的能力允许进行均相分析，这不需要分离和去除未结合的磁性颗粒。这项技术已经通过携带FLAG表位的脂质体模型系统进行了演示。鱿鱼显微镜需要不超过(5+/-2)×10(4)的磁性纳米颗粒来记录可重现的信号。
A technique is described for specific, sensitive, quantitative, and rapid detection of biological targets by using superparamagnetic nanoparticles and a "microscope" based on a high-transition temperature de superconducting quantum interference device (SQUID). In this technique, a mylar film to which the targets have been bound is placed on the microscope. The firm, at room temperature and atmospheric pressure, is typically 40 mum from the SQUID, which is at 77 K in a vacuum. A suspension of magnetic nanoparticles carrying antibodies directed against the target is added to the mixture in the well, and 1-s pulses of magnetic field are applied parallel to the SQUID. In the presence of this aligning field the nanoparticles develop a net magnetization, which relaxes when the field is turned off. Unbound nanoparticles relax rapidly by Brownian rotation and contribute no measurable signal. Nanoparticles that are hound to the target on the film are immobilized and undergo Neel relaxation, producing a slowly decaying magnetic flux, which is detected by the SQUID. The ability to distinguish between bound and unbound labels allows one to run homogeneous assays, which do not require separation and removal of unbound magnetic particles. The technique has been demonstrated with a model system of liposomes carrying the FLAG epitope. The SQUID microscope requires no more than (5 +/- 2) x 10(4) magnetic nanoparticles to register a reproducible signal.