Yeh Shih-Hao, Chou Kuang-Hua, Yang Ruey-Jen
Department of Engineering Science, National Cheng Kung University, Tainan, Taiwan.
Lab Chip. 2016 Mar 7;16(5):925-31. doi: 10.1039/c5lc01365h.
The lack of sensitivity is a major problem among microfluidic paper-based analytical devices (μPADs) for early disease detection and diagnosis. Accordingly, the present study presents a method for improving the enrichment factor of low-concentration biomarkers by using shallow paper-based channels realized through a double-sided wax-printing process. In addition, the enrichment factor is further enhanced by exploiting the ion concentration polarization (ICP) effect on the cathodic side of the nanoporous membrane, in which a stationary sample plug is obtained. The occurrence of ICP on the shallow-channel μPAD is confirmed by measuring the current-voltage response as the external voltage is increased from 0 to 210 V (or the field strength from 0 to 1.05 × 10(4) V m(-1)) over 600 s. In addition, to the best of our knowledge, the electroosmotic flow (EOF) speed on the μPAD fabricated with a wax-channel is measured for the first time using a current monitoring method. The experimental results show that for a fluorescein sample, the concentration factor is increased from 130-fold in a conventional full-thickness paper channel to 944-fold in the proposed shallow channel. Furthermore, for a fluorescein isothiocyanate-labeled bovine serum albumin (FITC-BSA) sample, the proposed shallow-channel μPAD achieves an 835-fold improvement in the concentration factor. The concentration technique presented here provides a novel strategy for enhancing the detection sensitivity of μPAD applications.
在用于早期疾病检测和诊断的微流控纸基分析装置（μPADs）中，灵敏度不足是一个主要问题。因此，本研究提出了一种方法，通过使用双面蜡印工艺实现的浅纸基通道来提高低浓度生物标志物的富集因子。此外，通过利用纳米多孔膜阴极侧的离子浓度极化（ICP）效应进一步提高富集因子，在该效应中可获得固定的样品塞。通过在600秒内将外部电压从0增加到210 V（或场强从0增加到1.05×10⁴ V m⁻¹）时测量电流 - 电压响应，证实了浅通道μPAD上ICP的发生。此外，据我们所知，首次使用电流监测方法测量了用蜡通道制造的μPAD上的电渗流（EOF）速度。实验结果表明，对于荧光素样品，富集因子从传统全厚度纸通道中的130倍增加到所提出的浅通道中的944倍。此外，对于异硫氰酸荧光素标记的牛血清白蛋白（FITC - BSA）样品，所提出的浅通道μPAD在富集因子上实现了835倍的提升。这里提出的浓缩技术为提高μPAD应用的检测灵敏度提供了一种新策略。
