Wixforth Achim
University of Augsburg, Augsburg, Germany.
Methods Mol Med. 2005;114:121-45. doi: 10.1385/1-59259-923-0:121.
Microarray hybridization experiments are mostly based on quite small sample volumes being confined between the microarray itself and a cover slip or lifter slip on top of the narrow fluid layer. Under such conditions, the system is governed by the rules of microfluidics, i.e., by the regime of small Reynold's numbers. Here, diffusion is the only source for moving sample molecules toward their target spots. However, for a typical macromolecule such as that used in microarray hybridization experiments, the diffusion constant is very small. Hence, because they are driven by diffusion only, traveling over typical distances on a microarray may take them a very long time. Additionally, the slow time constants associated with the diffusion limit lead to pronounced depletion effects, which strongly influence the dynamics of a hybridization assay. In this report, we describe a novel technique to overcome the diffusion limit in microarray hybridization experiments. Surface acoustic waves on a piezoelectric substrate are coupled with the sample fluid on a microarray, where they act as a highly efficient agitation source. We demonstrate that the diffusion limit can be overcome in this fashion, leading to a remarkable increase in signal intensity and homogeneity in fluorescence-labeled microarray assays.
微阵列杂交实验大多基于相当小的样本体积，这些样本被限制在微阵列本身与覆盖在狭窄流体层顶部的盖玻片或升降片之间。在这种条件下，系统受微流体规则支配，即受小雷诺数 regime 支配。在此，扩散是使样本分子向其目标点移动的唯一来源。然而，对于微阵列杂交实验中使用的典型大分子而言，扩散常数非常小。因此，由于它们仅由扩散驱动，在微阵列上移动典型距离可能会花费很长时间。此外，与扩散极限相关的缓慢时间常数会导致明显的耗尽效应，这对杂交测定的动力学有强烈影响。在本报告中，我们描述了一种在微阵列杂交实验中克服扩散极限的新技术。压电基板上的表面声波与微阵列上的样本流体耦合，在那里它们充当高效搅拌源。我们证明以这种方式可以克服扩散极限，从而在荧光标记的微阵列测定中显著提高信号强度和均匀性。
