Center for International Research on Micronano Mechatronics (CIRMM), Institute of Industrial Science (IIS), the University of Tokyo, 4-6-1 Komaba Meguro, Tokyo, 153-8505, Japan.
Lab Chip. 2011 Dec 21;11(24):4187-93. doi: 10.1039/c1lc20608g. Epub 2011 Oct 28.
We have developed a highly mass-sensitive cantilever resonating at the interface of air and liquid. The cantilever is applicable as a biosensor by measuring its resonance frequency shift associated with the selective trapping of target molecules. One surface of the cantilever facing to the liquid is functionalized for label-free detection, while the opposite side is exposed to air to improve the resonance characteristics, such as the quality factor. The quality factor at resonance is 15, which is 50% higher than the same cantilever in liquid. The beam was excited through the photothermal effect of a power modulated laser and detected by laser Doppler velocimetry. Due to the proposed configuration, the signal-to-noise-ratio is 5.7 times larger than the completely submerged case. A micro-slit around the cantilever separates the air and liquid phases at a meniscus. We analyzed the cantilever motion including the meniscus membrane, and examined the effect of surface tension by applying various solutions. A slit width of 6 μm was found to give the best performance within the few prototypes. We measured the covalent immobilization of antibody molecules on a cantilever surface for three different concentrations: 20, 40, and 80 μg ml(-1). The kinetics measured by both resonance frequency shift of the cantilever and fluorescent intensity showed good agreement.
我们开发了一种在空气和液体界面处共振的高灵敏悬臂梁。通过测量与目标分子选择性捕获相关的共振频率偏移，该悬臂梁可用作生物传感器。悬臂梁面向液体的一侧进行了无标记检测功能化处理，而另一侧暴露于空气中以提高共振特性，如品质因数。共振时的品质因数为 15，比在液体中的相同悬臂梁高出 50%。梁通过功率调制激光的光热效应激励，并通过激光多普勒测速法检测。由于采用了这种结构，信号噪声比是完全浸没情况下的 5.7 倍。悬臂梁周围的微狭缝在弯月面处将空气和液相分开。我们分析了包括弯月膜在内的悬臂梁运动，并通过施加各种溶液来检查表面张力的影响。在几个原型中，发现狭缝宽度为 6μm 时性能最佳。我们测量了三种不同浓度（20、40 和 80μgml(-1)）的抗体分子在悬臂梁表面的共价固定化。通过悬臂梁共振频率偏移和荧光强度测量的动力学都表现出很好的一致性。
