A double signal amplification-based homogeneous electrochemical sensor built on catalytic hairpin assembly and bisferrocene markers.

A facile, sensitive and unmodified Hg homogeneous electrochemical sensor based on bisferrocene signal markers and catalytic hairpin self-assembly (CHA) was built on a gold disk electrode. Three hairpin probes were designed, in which thiol was labeled at both ends of the hairpin probe 1(HP1), while bisferrocene, a redox signal marker, was labeled at both ends of the hairpin probe 2(HP2) and hairpin probe 3(HP3). Due to the Hg mediated thymine-Hg (II)-thymine (T-Hg-T) structure, when Hg is introduced, the T-Hg-T that occurred between the probe DNA and helper DNA could open the hairpin structure of probe DNA and form a rigid DNA triangles structure by CHA.