A strategy for the development of small-molecule-based sensors that strongly fluoresce when bound to a specific RNA.

We report a broadly applicable approach for the development of small-molecule-based RNA sensors. Our photoinduced electron transfer (PET) sensor consists of a fluorescein derivative as the fluorophore and two aniline derivatives as electron donors (quenchers). The isolation of electron-donor-binding RNA by in vitro selection (also known as SELEX) yielded an RNA aptamer that could increase the fluorescence intensity of the sensor by 13-fold. This result shows that RNA-electron-donor interactions can be used to develop modular RNA chemosensors.