Lead contamination in drinking water is a primary concern in public health, but it is difficult to monitor by end-users. Here, we provide a rapid and power-free microfluidic particle dam which enables visual quantification of lead ions (Pb2+) by the naked eye. GR-5 DNAzyme with extended termini can connect magnetic microparticles (MMPs) and polystyrene microparticles (PMPs) by DNA hybridization, forming "MMPs-GR-5-PMPs". When Pb2+ is present, GR-5 is cleaved, resulting in an increasing number of free PMPs. To visually count the free PMPs, the solution is loaded to a capillary-driven microfluidic device that consists of a magnetic separator to remove the MMPs-GR-5-PMPs, followed by a particle dam that traps and accumulates the free PMPs into a visual bar with growing length proportional to the concentration of lead. The device achieved a limit of detection at 2.12 nM (0.44 ppb), high selectivity (>20,000-fold) against other metal ions, high tolerance to different pH and water hardness, and is compatible with tap water with a high recovery rate, enabling visual quantification and user-friendly interface for rapid screening of water safety.

中文翻译：

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微流控粒子坝，用于视觉和定量检测铅离子。

饮用水中的铅污染是公共卫生中的首要问题，但最终用户很难对其进行监控。在这里，我们提供了一种快速且无功率的微流体微粒坝，该坝可通过肉眼目测量化铅离子（Pb2 +）。具有延伸末端的GR-5 DNAzyme可通过DNA杂交连接磁性微粒（MMP）和聚苯乙烯微粒（PMP），形成“ MMPs-GR-5-PMP”。当存在Pb2 +时，GR-5裂解，导致游离PMP数量增加。为了直观地计数游离PMP，将溶液加载到毛细管驱动的微流控设备中，该设备由磁选机组成，以去除MMPs-GR-5-PMP，然后是颗粒坝，将游离PMP捕集并累积到可见物中。长度与铅浓度成正比的金属条。