RNA Mango-based Sensors for Lead

Lead (Pb2+) toxicity poses a serious threat to human health and remains a global concern; therefore, there is a critical need for the development of easy-to-use and cost-effective tools for the rapid monitoring of Pb2+. In this study, we demonstrate the potential of the RNA Mango aptamer as a sensitive and selective sensor for Pb2+. Our findings reveal that trace amounts of Pb2+ induce the formation of the G-quadruplex motif in RNA Mango, which facilitates dye binding and activates fluorescence. A detailed investigation of the fluorescence properties of RNA Mango with three different dyes, TO1-Biotin, TO3-Biotin, and Thioflavin-T, in the presence of Pb2+ shows that RNA Mango has the highest binding affinity for Pb2+ in combination with TO1-Biotin, with a KD value as low as [~]100 nM. In the presence of Pb2+, RNA Mango has sub-micromolar affinity for all three dyes, showing the tightest binding to TO1-Biotin (KD [~]40 nM). Mango lead sensors detect low nanomolar concentrations of Pb2+ with limits of detection of 2 - 16 nM, which are significantly lower than its allowable limit in drinking water. RNA Mango exhibits remarkable selectivity toward Pb2+ and can detect lead in tap water samples. This work reports a new class of simple and inexpensive fluorescence-based sensors for lead and expands the repertoire of RNA-based lead sensors.