核磁共振技术（NMR）是目前普遍使用的蛋白质和其他分子结构的鉴定方法。但当前利用该技术探测蛋白分子结构需要两个条件：贵重的大型设备以及大量的蛋白质样本（约1017）。
美国麻省理工学院（MIT）比特和原子研究中心（Center for Bits and Atoms）的科学家利用微探测器开发出了一种新方法，从根本上改进了核磁共振技术的检测效率和实用性。该研究在线发表于5月14日当周的《美国国家科学院院刊》（PNAS）上。
该论文作者之一、MIT生物工程中心副主任张曙光称此次研究是“革命性”的。传统的NMR探针是由围绕着研究样本的一个线圈构成的，它产生的磁场能够与样品中的原子核自旋发生作用，从而揭示其分子构造。
在新的研究中，MIT的访问学者Yael Maguire试图利用其他方法来替代线圈探针。新的探针是一条平平的金属带，研究人员用激光在上面开出了一个小槽，形成了微带线（strip line）。“漏出”微带线外的磁场区域将金属带变成优良的探针。
该新型探测器看上去有信用卡的三分之一大，制作简单且成本较低。尽管该探测器目前仍必须安装在产生超导磁场的大型仪器上，不过新的技术有望促使体积更小的桌上型核磁共振设备的出现。
张曙光表示，新的核磁共振设备将对由蛋白质折叠导致的疾病的诊断产生重大影响，比如阿尔海默症、亨廷顿舞蹈症以及一些神经退行性疾病等。同时，新技术还将显著地提高生物医学研究效率，并为便携式疾病诊断和土壤分析工具的出现开辟了一条新的道路。
原始出处：
PNAS，Published online before print May 15, 2007
Proc. Natl. Acad. Sci. USA, 10.1073/pnas.0703001104
Applied Physical Sciences
Ultra-small-sample molecular structure detection using microslot waveguide nuclear spin resonance
( inductive microslot | miniature probe fabrication | nanomole RNAase-A structural detection | nuclear magnetic resonance scaling | ultra-sensitivity )
Yael Maguire * , Isaac L. Chuang *, Shuguang Zhang * , and Neil Gershenfeld *
*Center for Bits and Atoms and Center for Biomedical Engineering, NE47-379, Massachusetts Institute of Technology, Cambridge, MA 02139-4307
Communicated by Alexander Rich, Massachusetts Institute of Technology, Cambridge, MA, April 6, 2007 (received for review August 25, 2006)
Abstract
We here report on the design of a planar microslot waveguide NMR probe with an induction element that can be fabricated at scales from centimeters to nanometers to allow analysis of biomolecules at nano- or picomole quantities, reducing the required amount of materials by several orders of magnitude. This device demonstrates the highest signal-to-noise ratio for a planar detector to date, measured by using the anomeric proton signal from a 15.6-nmol sample of sucrose. This probe had a linewidth of 1.1 Hz for pure water without susceptibility matching. Analysis of 1.57 nmol of ribonuclease-A shows high sensitivity in one- and two-dimensional NMR spectra. Along with reducing required sample volumes, this integrated geometry can be packed in parallel arrays and combined with microfluidic systems. Further development of this device may have broad implications not only for advancing our understanding of many intractable protein structures and their folding, molecular interactions, and dynamic behaviors, but also for high-sensitivity diagnosis of a number of protein conformational diseases.
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