Department of Chemistry, University of Toronto, 80 St George St., Toronto, ON M5S 3H6, Canada.
Lab Chip. 2017 Jun 27;17(13):2272-2280. doi: 10.1039/c7lc00440k.
Microfluidic platforms are an attractive option for incorporating complex fluid handling into low-cost and rapid diagnostic tests. A persistent challenge for microfluidics, however, is the mismatch in the "world-to-chip" interface - it is challenging to detect analytes present at low concentrations in systems that can only handle small volumes of sample. Here we describe a new technique termed pre-concentration by liquid intake by paper (P-CLIP) that addresses this mismatch, allowing digital microfluidics to interface with volumes on the order of hundreds of microliters. In P-CLIP, a virtual microchannel is generated to pass a large volume through the device; analytes captured on magnetic particles can be isolated and then resuspended into smaller volumes for further processing and analysis. We characterize this method and demonstrate its utility with an immunoassay for Plasmodium falciparum lactate dehydrogenase, a malaria biomarker, and propose that the P-CLIP strategy may be useful for a wide range of applications that are currently limited by low-abundance analytes.
微流控平台是将复杂的流体处理技术集成到低成本、快速诊断测试中的一种有吸引力的选择。然而，微流控技术面临的一个持续挑战是“从世界到芯片”接口的不匹配——在只能处理小体积样本的系统中，检测低浓度存在的分析物具有挑战性。在这里，我们描述了一种新的技术，称为通过纸张吸入进行预浓缩（P-CLIP），该技术解决了这种不匹配问题，允许数字微流控与数百微升量级的体积相接口。在 P-CLIP 中，生成一个虚拟微通道以通过设备传递大体积；可以捕获到磁性粒子上的分析物，并将其重新悬浮到较小的体积中，以进行进一步的处理和分析。我们对该方法进行了表征，并通过针对疟原虫乳酸脱氢酶（一种疟疾生物标志物）的免疫分析证明了其效用，并提出 P-CLIP 策略可能对目前受到低丰度分析物限制的广泛应用有用。
