Department of Mechanical Engineering, Stanford University, CA, USA.
Electrophoresis. 2011 Feb;32(5):563-72. doi: 10.1002/elps.201000338. Epub 2011 Feb 10.
We present a theoretical and experimental study on increasing the sensitivity of ITP assays by varying channel cross-section. We present a simple, unsteady, diffusion-free model for plateau mode ITP in channels with axially varying cross-section. Our model takes into account detailed chemical equilibrium calculations and handles arbitrary variations in channel cross-section. We have validated our model with numerical simulations of a more comprehensive model of ITP. We show that using strongly convergent channels can lead to a large increase in sensitivity and simultaneous reduction in assay time, compared to uniform cross-section channels. We have validated our theoretical predictions with detailed experiments by varying channel geometry and analyte concentrations. We show the effectiveness of using strongly convergent channels by demonstrating indirect fluorescence detection with a sensitivity of 100 nM. We also present simple analytical relations for dependence of zone length and assay time on geometric parameters of strongly convergent channels. Our theoretical analysis and experimental validations provide useful guidelines on optimizing chip geometry for maximum sensitivity under constraints of required assay time, chip area and power supply.
我们提出了一种通过改变通道横截面来提高 ITP 分析灵敏度的理论和实验研究。我们提出了一种简单的、非稳态的、无扩散的模型，用于描述轴向变截面通道中的平台模式 ITP。我们的模型考虑了详细的化学平衡计算，并处理了通道横截面的任意变化。我们通过对 ITP 更全面模型的数值模拟验证了我们的模型。我们表明，与均匀横截面通道相比，使用强收敛通道可以显著提高灵敏度，同时缩短分析时间。我们通过改变通道几何形状和分析物浓度的详细实验验证了我们的理论预测。我们通过演示灵敏度为 100 nM 的间接荧光检测展示了使用强收敛通道的有效性。我们还提出了用于强收敛通道的简单分析关系，用于分析区长度和分析时间对强收敛通道几何参数的依赖性。我们的理论分析和实验验证为在所需分析时间、芯片面积和电源的限制下优化芯片几何形状以获得最大灵敏度提供了有用的指导。
