Detection of Pb2+ in Aqueous Solution by Using a DNA-modified Microcantilever

We developed a novel Pb2+-sensor based on a microcantilever that was modified with a specific Pb2+-dependent DNAzyme molecule. This microcantilever sensor could detect Pb2+ sensitively and selectively in an aqueous solution. Upon complexation with Pb2+, the DNAzyme duplex unwinded and formed a G-quadruplex conformation, which led to an increase of repulsion between the DNAzyme molecules and a subsequent bending of the microcantilever. This microcantilever sensor could be regenerated, flowing through a strong Pb2+ chelator, 1,4,7,10-tetraazacyclododecane- 1,4,7,10-tetraacetic acid. The detection limit of the microcantilever sensor for Pb2+ ions is as low as 10−8 M. The microcantilever sensor also exhibited a high selectivity to Pb2+ over other metal ions such as Mg2+, Fe3+, Zn2+, Ca2+, and Cd2+.