High-Throughput Development and Optimization of RNA-Based Fluorogenic Biosensors of Small Molecules Using Droplet-Based Microfluidics.

Small-molecule sensing is a major issue as they can serve both in fundamental science and as makers of various diseases, contaminations, or even environment pollution. RNA aptamers are single-stranded nucleic acids that can adopt different conformations and specifically recognize a wide range of ligands, making them good candidates to develop biosensors of small molecules. Recently, light-up RNA aptamers have been introduced and used as starting building blocks of RNA-based fluorogenic biosensors. They are typically made of three domains: a reporter domain (a light-up aptamer), connected to a sensor domain (another aptamer) via a communication module. The latter is instrumental as being in charge of information transmission between the sensor and the reporting domains. Here we present an ultrahigh-throughput screening procedure to develop RNA-based fluorogenic biosensors by selecting optimized communication modules through an exhaustive functional exploration of every possible sequence permutation using droplet-based microfluidics and next-generation sequencing.