Department of Biomedical Engineering, City University of Hong Kong, Hong Kong, Hong Kong.
Mikrochim Acta. 2021 Apr 27;188(5):176. doi: 10.1007/s00604-021-04822-0.
A portable biosensor has been developed based on microfluidic particle accumulation for visual quantification of copper ions. A copper-dependent DNAzyme is used to connect magnetic microparticles (MMPs) and polystyrene microparticles (PMPs), forming "MMPs-DNAzyme-PMPs." When copper ions are present, the DNAzyme is cleaved, allowing free PMPs to be released from the MMPs-DNAzyme-PMP complex. Using a capillary-flow-based microfluidic device, the MMPs-DNAzyme-PMPs are first separated by a magnetic chamber, allowing the free PMPs to continue flowing until being trapped at a particle dam with a narrowing nozzle. Therefore, as a thermometer-like display, the copper level can be visually quantified by the accumulation length of the free PMPs in the trapping microchannel. The limit of detection (LOD) is 33 nM determined by the linear range of 25-100 nM, which is 900 times lower than the prevalent standard (~30 μM) in Hong Kong. The system shows excellent selectivity (> 1000-folds) against other heavy metal ions and abilities to adapt to multiple water environmental conditions. Tests on tap water samples and three local natural water sources in Hong Kong manifest that the device can effectively monitor the quality of freshwater with >70% recovery and 26.16% RSD.
一种基于微流控粒子堆积的便携式生物传感器已被开发出来，用于可视化定量检测铜离子。一种依赖铜的 DNA 酶被用于连接磁性微球（MMPs）和聚苯乙烯微球（PMPs），形成“MMPs-DNAzyme-PMPs”。当存在铜离子时，DNA 酶被切割，允许游离的 PMPs从 MMPs-DNAzyme-PMP 复合物中释放出来。使用基于毛细管流动的微流控装置，MMPs-DNAzyme-PMPs 首先在磁室中分离，允许游离的 PMPs 继续流动，直到在具有缩口喷嘴的粒子坝中被捕获。因此，作为一种类似于温度计的显示器，可以通过在捕获微通道中自由 PMPs 的积累长度来直观地定量铜水平。通过 25-100 nM 的线性范围确定检测限（LOD）为 33 nM，比香港普遍的标准（~30 μM）低 900 倍。该系统对其他重金属离子具有出色的选择性（>1000 倍），并能够适应多种水环境污染条件。对自来水样和香港三个本地天然水源的测试表明，该设备可以有效地监测淡水的质量，回收率>70%，相对标准偏差（RSD）为 26.16%。
