標題: | A highly efficient bead extraction technique with low bead number for digital microfluidic immunoassay |
作者: | Huang, Cheng-Yeh Tsai, Po-Yen Lee, I-Chin Hsu, Hsin-Yun Huang, Hong-Yuan Fan, Shih-Kang Yao, Da-Jeng Liu, Cheng-Hsien Hsu, Wensyang 機械工程學系 應用化學系 Department of Mechanical Engineering Department of Applied Chemistry |
公開日期: | 一月-2016 |
摘要: | Here, we describe a technique to manipulate a low number of beads to achieve high washing efficiency with zero bead loss in the washing process of a digital microfluidic (DMF) immunoassay. Previously, two magnetic bead extraction methods were reported in the DMF platform: (1) single-side electrowetting method and (2) double-side electrowetting method. The first approach could provide high washing efficiency, but it required a large number of beads. The second approach could reduce the required number of beads, but it was inefficient where multiple washes were required. More importantly, bead loss during the washing process was unavoidable in both methods. Here, an improved double-side electrowetting method is proposed for bead extraction by utilizing a series of unequal electrodes. It is shown that, with proper electrode size ratio, only one wash step is required to achieve 98% washing rate without any bead loss at bead number less than 100 in a droplet. It allows using only about 25 magnetic beads in DMF immunoassay to increase the number of captured analytes on each bead effectively. In our human soluble tumor necrosis factor receptor I (sTNF-RI) model immunoassay, the experimental results show that, comparing to our previous results without using the proposed bead extraction technique, the immunoassay with low bead number significantly enhances the fluorescence signal to provide a better limit of detection (3.14 pg/ml) with smaller reagent volumes (200 nl) and shorter analysis time (<1 h). This improved bead extraction technique not only can be used in the DMF immunoassay but also has great potential to be used in any other bead-based DMF systems for different applications. (C) 2016 AIP Publishing LLC. |
URI: | http://dx.doi.org/10.1063/1.4939942 http://hdl.handle.net/11536/135389 |
ISSN: | 1932-1058 |
DOI: | 10.1063/1.4939942 |
期刊: | BIOMICROFLUIDICS |
Volume: | 10 |
Issue: | 1 |
顯示於類別: | 會議論文 |