Graphene and Anthraquinone-2-sulfonic Acid Sodium Based Electrochemical Aptasensor for Pb~(2+)
An electrochemical aptasensor for Pb2 +was constructed based on the layer-by-layer assembly of graphene(GR) and anthraquinone-2-sulfonic acid sodium salt(AQMS) on the surface of Pb2 +aptamer. The mercapto-modified Pb2 +aptamer was first anchored on a gold electrode. Then the highly conductive material of GR was adsorbed on apt through the unique π-π stacking interaction,which was further used for the assembly and signal amplification of the electroactive AQMS. Upon interaction with Pb2 +ions,the apt on the aptasensor undergone conformational switch from a single-stranded form to the G-quadruplex structure,causing the GR assembled with AQMS releasing from the electrode surface into solution. As a result,the electrochemical signal of AQMS on the aptasensor was substantially reduced. Base on this concept,a useful platform for detection of Pb2 +ions was constructed. Under the optimal experimental conditions,the attenuation of peak currents(ΔIpa) showed linear relationship with the logarithm of Pb2 +concentrations(lgCPb2 +) over the range from 5.0 ×10!10to 5. 0 × 10!8mol / L. The detection limit was estimated to be 6. 0 × 10!11mol / L.