Lack of access to safe drinking water is a global problem, and methods to reliably and easily detect contaminants could be transformative. We report the development of a cell-free in vitro transcription system that uses RNA Output Sensors Activated by Ligand Induction (ROSALIND) to detect contaminants in water. A combination of highly processive RNA polymerases, allosteric protein transcription factors and synthetic DNA transcription templates regulates the synthesis of a fluorescence-activating RNA aptamer. The presence of a target contaminant induces the transcription of the aptamer, and a fluorescent signal is produced. We apply ROSALIND to detect a range of water contaminants, including antibiotics, small molecules and metals. We also show that adding RNA circuitry can invert responses, reduce crosstalk and improve sensitivity without protein engineering. The ROSALIND system can be freeze-dried for easy storage and distribution, and we apply it in the field to test municipal water supplies, demonstrating its potential use for monitoring water quality.

缺乏安全饮用水是一个全球性问题，可靠而轻松地检测污染物的方法可能会带来变革。我们报告了无细胞体外转录系统的发展，该系统使用由配体诱导（ROSALIND）激活的RNA输出传感器来检测水中的污染物。高度合成的RNA聚合酶，变构蛋白转录因子和合成DNA转录模板的组合可调节荧光激活RNA适体的合成。目标污染物的存在诱导适体的转录，并产生荧光信号。我们将ROSALIND用于检测多种水污染物，包括抗生素，小分子和金属。我们还表明，添加RNA电路可以逆转反应，无需蛋白质工程，即可降低串扰并提高灵敏度。ROSALIND系统可以冷冻干燥，以便于存储和分配，我们将其应用于野外测试市政供水，证明了其在监测水质方面的潜在用途。