Nordling John, Millen Rachel L, Bullen Heather A, Porter Marc D, Tondra Mark, Granger Michael C
Department of Chemistry, Ames Laboratory--USDOE, and Institute for Combinatorial Discovery, Iowa State University, Ames, Iowa 50011, USA.
Anal Chem. 2008 Nov 1;80(21):7930-9. doi: 10.1021/ac8009577. Epub 2008 Oct 1.
This paper describes efforts aimed at setting the stage for the application of giant magnetoresistance sensor (GMRs) networks as readers for quantification of biolytes selectively captured and then labeled with superparamagnetic particles on a scanned chip-scale array. The novelty and long-range goal of this research draws from the potential development of a card-swipe instrument through which an array of micrometer-sized, magnetically tagged addresses (i.e., a sample stick) can be interrogated in a manner analogous to a credit card reader. This work describes the construction and testing of a first-generation instrument that uses a GMR sensor network to read the response of a "simulated" sample stick. The glass sample stick is composed of 20-nm-thick films of permalloy that have square or rectangular lateral footprints of up to a few hundred micrometers. Experiments were carried out to gain a fundamental understanding of the dependence of the GMR response on the separation between, and planarity of, the scanned sample stick and sensor. Results showed that the complex interplay between these experimentally controllable variables strongly affect the shape and magnitude of the observed signal and, ultimately, the limit of detection. This study also assessed the merits of using on-sample standards as internal references as a facile means to account for small variations in the gap between the sample stick and sensor. These findings were then analyzed to determine various analytical figures of merit (e.g., limit of detection in terms of the amount of magnetizable material on each address) for this readout strategy. An in-depth description of the first-generation test equipment is presented, along with a brief discussion of the potential widespread applicability of the concept.
本文介绍了一系列工作，旨在为应用巨磁阻传感器（GMR）网络搭建基础，该网络将作为读取器，用于对生物分子进行定量分析。这些生物分子被选择性捕获，然后用超顺磁性颗粒标记在扫描芯片级阵列上。本研究的新颖之处和长远目标源自刷卡式仪器的潜在发展，通过这种仪器，可以以类似于信用卡读卡器的方式询问一系列微米级的磁性标记地址（即样品棒）。这项工作描述了第一代仪器的构建和测试，该仪器使用GMR传感器网络来读取“模拟”样品棒的响应。玻璃样品棒由厚度为20纳米的坡莫合金薄膜组成，其方形或矩形横向尺寸可达几百微米。进行实验以深入了解GMR响应与扫描的样品棒和传感器之间的间距及平面度的依赖关系。结果表明，这些实验可控变量之间的复杂相互作用强烈影响观察信号的形状和幅度，并最终影响检测限。本研究还评估了使用样品上的标准作为内部参考的优点，这是一种简便的方法，可用于考虑样品棒与传感器之间间隙的微小变化。然后分析这些结果，以确定这种读出策略的各种分析性能指标（例如，根据每个地址上可磁化材料的量确定检测限）。本文详细介绍了第一代测试设备，并简要讨论了该概念潜在的广泛适用性。
