Department of Chemical and Biomolecular Engineering , North Carolina State University , 911 Partners Way, Campus Box 7905 , Raleigh , North Carolina 27695 , United States.
Department of Electrical and Computer Engineering , North Carolina State University , 890 Oval Drive , Raleigh , North Carolina 27606 , United States.
Anal Chem. 2019 Aug 20;91(16):10448-10457. doi: 10.1021/acs.analchem.9b00750. Epub 2019 Jun 27.
Developing easy-to-use and miniaturized detectors is essential for in-field monitoring of environmentally hazardous substances, such as the cyanotoxins. We demonstrated a differential fluorescent sensor array made of aptamers and single-stranded DNA (ssDNA) dyes for multiplexed detection and discrimination of four common cyanotoxins with an ordinary smartphone within 5 min of reaction. The assay reagents were preloaded and dried in a microfluidic chip with a long shelf life over 60 days. Upon the addition of analyte solutions, competitive binding of cyanotoxin to the specific aptamer-dye conjugate occurred. A zone-specific and concentration-dependent reduction in the green fluorescence was observed as a result of the aptamer conformation change. The aptasensors are fully optimized by quantification of their dissociation constants, tuning the stoichiometric ratios of reaction mixtures, and implementation of an internal intensity correction step. The fluorescent sensor array allowed for accurate identification and measurement of four important cyanotoxins, including anatoxin-a (ATX), cylindrospermopsin (CYN), nodularin (NOD), and microcystin-LR (MC-LR), in parallel, with the limit of detection (LOD) down to a few nanomolar (<3 nM), which is close to the World Health Organization's guideline for the maximum concentration allowed in drinking water. The smartphone-based sensor platform also showed remarkable chemical specificity against potential interfering agents in water. The performance of the system was tested and validated with real lake water samples that were contaminated with trace levels of individual cyanotoxins as well as binary, ternary, and quaternary mixtures. Finally, a smartphone app interface has been developed for rapid on-site data processing and result display.
开发易于使用和小型化的探测器对于现场监测环境危害物质（如蓝藻毒素）至关重要。我们展示了一种由适体和单链 DNA（ssDNA）染料组成的差分荧光传感器阵列，可在 5 分钟的反应时间内使用普通智能手机对四种常见蓝藻毒素进行多重检测和区分。该测定试剂预先加载并干燥在微流控芯片中，具有超过 60 天的长保质期。加入分析物溶液后，蓝藻毒素与特定适体-染料缀合物发生竞争性结合。由于适体构象变化，观察到绿色荧光的区域特异性和浓度依赖性降低。通过量化其解离常数、调整反应混合物的化学计量比以及实施内部强度校正步骤，对适体传感器进行了全面优化。荧光传感器阵列允许对四种重要的蓝藻毒素（包括anatoxin-a [ATX]、cylindrospermopsin [CYN]、nodularin [NOD]和 microcystin-LR [MC-LR]）进行准确识别和测量，同时具有低至几个纳摩尔（<3 nM）的检测限，接近世界卫生组织饮用水允许的最高浓度指南。基于智能手机的传感器平台还表现出对水中潜在干扰剂的显著化学特异性。该系统的性能已通过受痕量单一蓝藻毒素以及二元、三元和四元混合物污染的实际湖水样本进行了测试和验证。最后，开发了一个智能手机应用程序界面，用于快速现场数据处理和结果显示。
