Measurement of the surface concentration for bloassay kinetics in microchannels
Measurement of the surface concentration for bloassay kinetics in microchannels
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DOI：
10.1021/ac048996
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发表时间：
2005-02-01
影响因子：
7.4
通讯作者：
Viovy, JL
中科院分区：
文献类型：
--
作者：
Bancaud, A;Wagner, G;Viovy, JL
我们提出了一种基于荧光显微镜的简单而通用的方法来可靠地测量微通道中表面附近的平流分子的浓度。该工具与许多微流控应用相关，例如免疫分析和单分子实验，在这些实验中，人们可以探测固定化目标和主体流动携带的反应物之间的反应动力学。表面浓度的表征突出了横向扩散的主导作用，在表面产生的表观扩散系数比单独的分子扩散大3-4个数量级，甚至接近注入点。我们直接测量了沿通道的纵向位置和流量对浓度前沿的影响，并建立了一个简单的分析模型，与数据进行了很好的比较。最后，我们提出了一种在单分子测量中正确解释浓度前沿的方法，并使用它来直接获取鱼精蛋白诱导的DNA缩合的动力学参数。
We present a simple and versatile method, based on fluorescence microscopy, to reliably measure the concentration of advected molecules in the vicinity of surfaces in microchannels. This tool is relevant to many microfluidic applications such as immunoassays and single-molecule experiments, where one probes the kinetics of a reaction between an immobilized target and a reactant carried by the bulk flow. The characterization of the surface concentration highlights the dominant role of transverse diffusion, which generates an apparent diffusivity at the surface 3-4 orders of magnitude greater than molecular diffusion alone, even close to the point of injection. We directly measure the effects of the longitudinal position along the channel and of the flow rate on the concentration front and develop a simple analytical model that compares well with the data. Finally, we propose a method to properly account for concentration fronts in single-molecule measurements and use it to directly access the kinetics parameters of protamine-induced condensation of DNA.