A novel electrochemical biosensor for selective determination of mercury ions based on DNA hybridization

An electrochemical biosensor was developed for Hg2+ determination based on DNA hybridization. In the presence of Hg2+, the target and probe DNAs with thymine–thymine (T–T) mismatches could hybridize by forming T–Hg2+–T complex. This induced DNA hybridization led to the decrease in reduction peak currents of ethyl green (EG) as electroactive label, which could be used for determination of Hg2+. The difference in the value of the peak currents of EG before and after DNA hybridization (ΔI) was linear with the concentration of Hg2+ in the range of 9.0 × 10−11–1.0 × 10−9 M. The detection limit was 3.08 × 10−11 M.