Electrogenerated chemiluminescence biosensor for detection of mercury (II) ion via target-triggered manipulation of DNA three-way junctions.

A new electrogenerated chemiluminescence (ECL) biosensor is fabricated for the determination of mental ion incorporating DNA three-way junction structure (DNA-TWJ). As a model system, Hg2+ was chosen as an analyte. The ECL biosensor was fabricated by covalently coupling Hg2+ special DNA-TWJ tagged with ruthenium (II) complex (Ru) (named TW/Ru-J1) to the surface of glassy carbon electrode that had been covalently modified with 4-aminobenzoic acid via electrochemical oxidations. Upon binding of Hg2+ to the TW/Ru-J1, the confirmation of TW/Ru-J1 changed and induced Ru away from surface of electrode and thus led to a low ECL signal. The signal linearly decreases with the concentration of Hg2+ in the range from 0.1 pM to 10 pM with a detection limit of 0.04 pM This study could be easily extended to various analytical platforms for the detection of many kinds of analytes or their interactions such as DNA/RNA, DNAzyme/target, aptamer/target, and antibody/antigen.