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

An electrochemical biosensor was developed for Hg(2+) determination based on DNA hybridization. In the presence of Hg(2+), the target and probe DNAs with thymine-thymine (T-T) mismatches could hybridize by forming T-Hg(2+)-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 Hg(2+). The difference in the value of the peak currents of EG before and after DNA hybridization (ΔI) was linear with the concentration of Hg(2+) in the range of 9.0 × 10(-11)-1.0 × 10(-9) M. The detection limit was 3.08 × 10(-11) M.