Label free electrochemical sensor for Pb2+ based on graphene oxide mediated deposition of silver nanoparticles

By the use of graphene oxide (GO) as catalytic probe and deposition substrate, a novel label free electrochemical biosensor has been fabricated for sensitive detection of Pb2+. As a result of Pb2+ induced conformational change of aptamer, GO can be captured on electrode surface. The Ag+ reduction process can be accelerated by the captured GO, which resulted in the formation of silver nanoparticles (AgNPs) on GO surface. Through detecting the oxidation signal of the formed AgNPs by voltammetry, highly sensitive detection of Pb2+ can be realized. The detection limit of this assay for Pb2+ was 80 pM with a linear range from 0.1 nM to 10.0 μM. The developed sensor is simple, sensitive, selective, and do not need complex tagging process, thus holds great potential for Pb2+ and other molecular detection in real samples.