An ultrasensitive sensing strategy for the detection of lead (II) ions based on the intermolecular G-quadruplex and graphene oxide

• Graphene oxide was adopted as the fluorescence quencher.
• Dye-labeled AGRO100 aptamers could be absorbed onto graphene oxide.
• AGRO100 can interact with Pb2+ to form an intermolecular G-quadruplex/Pb2+ complex.
• The fluorescence of dye-labeled AGRO100 aptamer was restored.

In this paper, a simple and sensitive sensing strategy for the determination of Pb2+ ions was designed, in which anticancer drug AGRO100, a guanine (G)-quadruplex DNA aptamer, was selected as the probe to detect Pb2+ ions and graphene oxide (GO) was adopted as the fluorescence quencher. A dye-labeled AGRO100 aptamer in a flexible single stranded state could be adsorbed on the surface of GO, and the fluorescence was quenched via Förster resonance energy transfer (FRET) from fluorescence dyes to GO. AGRO100 can interact with Pb2+ ions to form an intermolecular G-quadruplex/Pb2+ complex, which has a weaker binding affinity with GO. By this way, the dyes were kept away from the GO sheet and the fluorescence was restored. Thus the AGRO100 aptamer could be used as a fluorescence probe for the determination of Pb2+ ions. Under the optimized conditions, there was a good linear relationship between the fluorescence intensity of the dyes and the concentration of Pb2+ ions in the range from 0.75 to 6.0 nmol/L with a detection limit of 0.40 nmol/L.

Figure optionsDownload as PowerPoint slide