Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa, Israel.
Lab Chip. 2018 Mar 13;18(6):861-868. doi: 10.1039/c7lc01250k.
We present a novel microfluidic paper-based analytical device (μPAD) which utilizes the native high electroosmotic flow (EOF) in nitrocellulose to achieve stationary isotachophoresis (ITP) focusing. This approach decouples sample accumulation from the length of the channel, resulting in significant focusing over short channel lengths. We provide a brief theory for EOF-balanced ITP focusing under continuous injection from a depleting reservoir and present the design of a short (7 mm) paper-based microfluidic channel, which allows a 200 μL sample to be processed in approximately 6 min, resulting in a 20 000-fold increase in concentration - a full order of magnitude improvement compared to previous paper-based ITP devices. We show the stability of the assay over longer (40 min) durations of time, and using Morpholino probes, we present the applicability of the device for amplification-free detection of nucleic acids, with a limit-of-detection (LoD) of 5 pM in 10 min. Finally, we utilize the small footprint of the channel and show a multiplexed platform in which 12 assays operate in parallel in a 24-well plate format.
我们提出了一种新颖的基于微流控纸的分析装置（μPAD），它利用硝酸纤维素的固有高电动流（EOF）来实现固定等速电泳聚焦。这种方法将样品的积累与通道的长度解耦，从而在短通道长度下实现显著的聚焦。我们提供了一个关于连续从消耗池中进样时 EOF 平衡的 ITP 聚焦的简要理论，并展示了一个短（7mm）的基于纸张的微流控通道的设计，该通道允许在大约 6 分钟内处理 200μL 的样品，从而实现了 20,000 倍的浓度增加 - 与之前的基于纸张的 ITP 设备相比，这是一个完整的数量级的改进。我们展示了该分析方法在较长时间（40 分钟）内的稳定性，并且使用 Morpholino 探针，我们展示了该设备在无需扩增的情况下检测核酸的适用性，在 10 分钟内检测到 5pM 的下限。最后，我们利用通道的小占地面积，展示了一个多路复用平台，其中 12 个检测在 24 孔板格式中并行运行。
