Intellectual Ventures , Bellevue , Washington 98005 , United States.
University of Washington , Seattle , Washington 98195 , United States.
Anal Chem. 2018 Jun 5;90(11):6643-6650. doi: 10.1021/acs.analchem.8b00440. Epub 2018 May 4.
Lateral flow assays (LFAs) are widely used for yes/no detection of analytes, but they are not well-suited for quantification. We show that the sensitivity of the test line in a lateral flow assay can be tuned to appear at a specific sample concentration by varying the density of capture molecules at the test line and that when test lines tuned for different responses are combined into a single test strip, lines appear at specific thresholds of sample concentration. We also developed a model based on mass-action kinetics that accurately described test line signal and shape over a wide matrix of capture molecules and sample concentrations in single-line strips. The model was used to design a three-line test strip with lines designed to appear at logarithmically spaced sample concentrations, and the experiments showed a remarkable match to predictions. The response of this "graded ladder bar" format is due to the effect of test line concentration on capture efficiency at each test line, not on sample depletion effects, and the effect is maintained whether a system is under kinetic or equilibrium control. These features enable design of nonlinear responses (logarithmic here) and suggest robustness for different systems. Thus, the graded ladder bar format could be a useful tool for applications requiring quantification of sample concentrations over a wide dynamic range.
侧向流动分析（LFA）广泛用于分析物的是/否检测，但不适合定量。我们表明，通过改变测试线上捕获分子的密度，可以调整侧向流动分析中测试线的灵敏度，使其在特定的样品浓度下出现，并且当针对不同响应的测试线组合成单个测试条时，线条会出现在样品浓度的特定阈值处。我们还开发了一个基于质量作用动力学的模型，该模型可以准确描述在单一线条中捕获分子和样品浓度的广泛矩阵中测试线信号和形状。该模型用于设计具有三线的测试条，这些线旨在在对数间隔的样品浓度下出现，实验结果与预测非常吻合。这种“分级梯条”格式的响应是由于测试线浓度对每个测试线的捕获效率的影响，而不是对样品消耗效应的影响，并且无论系统处于动力学还是平衡控制下，这种效应都得以维持。这些特性使非线性响应（此处为对数）的设计成为可能，并为不同的系统提供了稳健性。因此，分级梯条格式可能是需要在广泛动态范围内定量样品浓度的应用的有用工具。
