Amplified electrochemical sensing of lead ion based on DNA-mediated self-assembly-catalyzed polymerization

Lead ion (Pb2+, a heavy metal ion existed every aspect of life) is one of the most important hazards for environment and human health. Herein we design an in-situ amplified electronic monitoring system for sensitive determination of Pb2+ on Pb2+-specific DNAzyme-modified sensing interface. The assay consists of target-triggered cleavage of Pb2+-specific DNAzyme, initiator strand-induced DNA hybridization chain reaction, formation of hemin/G-quadruplex -based DNAzyme and its automatically catalyzed polymerization of aniline monomer along the double-stranded DNA. Experimental results indicated that the catalytic currents of the as-produced polyaniline were linearly dependent on target Pb2+ concentrations from 0.05 to 50 nM with a detection limit (LOD) of 32 pM. Such a synergistic effect of hybridization chain reaction with DNAzyme-catalyzed polymerization provided a universal platform for sensitive screening of target Pb2+, thereby holding great promise for application in practice.