Label-free selective sensing of Pb2＋ lead（II） sensors based on the aggregation of a pyrene fluorescent probe

In the present work, we report a label-free fluo- rescence turn-on approach for the sensitive and selective sensing of Pb2＋. Pyrene with one positive charge was used as the fluorescent probe, and thrombin aptamer （TBA）, which was a G-rich oligonucleotide, was employed to form G-quadruplex with lead（II）. When TBA and Pb2＋ were mixed with lead（II） in an aqueous solution, it was folded into a stable G-quadruplex. Subsequently, a single-stranded nucleic acid-specific nuclease S1 was added. The G-quad- ruplex stabilized by Pb2＋ lead（II） had markedly a significant resistant ability to nuclease S1 digestion. However, in the absence of Pb2＋ lead（II）, no quadruplex or less stable quadruplex was formed and TBA was digested by nuclease S1 in 3 min under the optimized experimental conditions. Finally, pyrene probe was Pb2＋ lead（II）. Electrostatic mixed with oligonucleotide in interactions between oligonu- cleotide （a polyanion） and the probe induced the aggregation of the probe, which in turn produced strong emission of the strong pyrene excimer emission. The intensity of the induced excimer emission was directly proportional to the amount of Pb2＋ added. Our approach shows good selectivity and sen- sitivity for the detection of Pb2＋ with a limit of detection limit as low as 800 nmol/L.

Label-free selective sensing of Pb2＋ lead（II） sensors based on the aggregation of a pyrene fluorescent probe

Pyrene probe ； G-quadruplex - Pb2＋lead（II） ion ； Label free . Fluorescence detection