ROSALIND: Rapid Detection of Chemical Contaminants with In Vitro Transcription Factor-Based Biosensors.

ROSALIND (RNA Output Sensors Activated by Ligand Induction) is an in vitro biosensing system that detects small molecules using regulated transcription reactions. It consists of three key components: (1) RNA polymerases, (2) allosteric protein transcription factors, and (3) synthetic DNA transcription templates that together regulate the synthesis of a fluorescence-activating RNA aptamer. The system can detect a wide range of chemicals including antibiotics, small molecules, and metal ions. We have demonstrated that ROSALIND can be lyophilized and transported at ambient conditions for water testing on-site. Here, we describe how to set up a ROSALIND reaction for detecting various chemical contaminants in water using a model transcription factor as well as how to build a new ROSALIND sensor.