Droplet-based microfluidic systems offer a high potential for miniaturization and automation. Therefore, they are becoming an increasingly important tool in analytical chemistry, biosciences, and medicine. Heterogeneous assays commonly utilize magnetic beads as a solid phase. However, the sensitivity of state of the art microfluidic systems is limited by the high bead concentrations required for efficient extraction across the water–oil interface. Furthermore, current systems suffer from a lack of technical solutions for sequential measurements of multiple samples, limiting their throughput and capacity for automation. Taking advantage of the different wetting properties of hydrophilic and hydrophobic areas in the channels, we improve the extraction efficiency of magnetic beads from aqueous nanoliter-sized droplets by 2 orders of magnitude to the low μg/mL range. Furthermore, the introduction of a switchable magnetic trap enables repetitive capture and release of magnetic particles for sequential analysis of multiple samples, enhancing the throughput. In comparison to conventional ELISA-based sandwich immunoassays on microtiter plates, our microfluidic setup offers a 25–50-fold reduction of sample and reagent consumption with up to 50 technical replicates per sample. The enhanced sensitivity and throughput of this system open avenues for the development of automated detection of biomolecules at the nanoliter scale.

中文翻译：

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破坏界面：从纳升液滴中高效提取磁珠，以进行自动连续免疫分析。

基于液滴的微流体系统为小型化和自动化提供了巨大潜力。因此，它们正成为分析化学，生物科学和医学中越来越重要的工具。异质测定通常利用磁珠作为固相。但是，最新的微流控系统的灵敏度受到在水-油界面上进行有效萃取所需的高磁珠浓度的限制。此外，当前的系统缺乏用于顺序测量多个样品的技术解决方案，从而限制了它们的通量和自动化能力。利用通道中亲水和疏水区域的不同润湿特性，我们将纳升级水液滴中磁珠的提取效率提高了2个数量级，达到了低μg/ mL范围。此外，可切换式磁阱的引入使得能够重复捕获和释放磁性颗粒，以便对多个样品进行顺序分析，从而提高了通量。与在微量滴定板上基于常规ELISA的夹心免疫分析相比，我们的微流控设置可减少25–50倍的样品和试剂消耗，每个样品最多重复50次技术重复。该系统的增强的灵敏度和通量为开发纳升规模的生物分子自动检测开辟了道路。引入可切换式磁阱可以重复捕获和释放磁性颗粒，以便对多个样品进行顺序分析，从而提高了通量。与在微量滴定板上基于常规ELISA的夹心免疫分析相比，我们的微流控设置可减少25–50倍的样品和试剂消耗，每个样品最多可重复50次技术重复。该系统增强的灵敏度和通量为开发纳升规模的生物分子自动检测开辟了道路。引入可切换式磁阱可以重复捕获和释放磁性颗粒，以便对多个样品进行顺序分析，从而提高了通量。与在微量滴定板上基于常规ELISA的夹心免疫分析相比，我们的微流控设置可减少25–50倍的样品和试剂消耗，每个样品最多可重复50次技术重复。该系统增强的灵敏度和通量为开发纳升规模的生物分子自动检测开辟了道路。