Fluorescent Aptaswitch for Detection of Lead Ions.

Detection of metal ions has essential roles in biology, food industry, and environmental sciences. In this work, we developed a Pb 2+ detection strategy based on a fluorophore-tagged Pb 2+ -binding aptamer. The DNA aptamer changes its conformation on binding Pb 2+ , switching from an "off" state (low fluorescence) to an "on" state (high fluorescence). This method provides a quantitative readout with a detection limit of 468 nM, is highly specific to Pb 2+ when tested against other metal ions, and is functional in complex biofluids. Such metal sensing DNA aptamers could be coupled with other biomolecules for sense-and-actuate mechanisms in biomedical and environmental applications.