A convenient paper-based fluorescent aptasensor for high-throughput detection of Pb2+ in multiple real samples (water-soil-food)

Lead ion (Pb2+) is one of the most toxic and widely polluted heavy metal ions. Given the potential health risks and economic losses associated with Pb2+, the rapid detection of Pb2+ using fluorescent aptasensors is of significant importance in evaluating food safety. A rapid, facile and economic fluorescent aptasensor using convenient paper as the sensing substrate was designed to high-throughput detect Pb2+ in complex samples within about 45 min. The Pb2+ changed the conformation of FAM-modified Apt from a random coil to a stable G-quadruplex structure. And then Dabcyl-labeled cDNA was added to form double-stranded DNA with the Apt that did not form a G-quadruplex structure, resulting in a weak fluorescence due to the fluorescence resonance energy transfer (FRET). The fluorescent aptasensor showed a positive correlation with Pb2+ concentration, and a linear relationship was obtained in the range of 0.01-10 μM with LOD of 6.1 nM. In addition, this method has been successfully used for the determination of Pb2+ in water, soil and various foods containing complex substrates. Meanwhile, the high-throughput detection of Pb2+ has also reached an acceptable level. Therefore, this convenient strategy has potential application value for on-site rapid detection of Pb2+.