Abstract
A bidirectional self-powered biosensor is constructed for the quasi-simultaneous detection of Pb(2+) and Hg(2+) based on MoS(2)@CuS heterostructures as an accelerator and hybridization chain reaction (HCR) as a signal amplification strategy. MoS(2)@CuS heterostructures significantly facilitate electron transfer between glucose and bioelectrodes, thereby greatly improving the detection signal of self-powered biosensors. This novel biosensor employs the unique sequences of DNAzymes to isolate Pb(2+) and Hg(2+) by the cleavage effect and thymine (T)-Hg(2+)-thymine (T) structures, respectively. In the process, Pb(2+) cuts the sequence of DNAzyme at the bioanode to trigger glucose oxidation to monitor Pb(2+). The as-formed T-Hg(2+)-T structures activate HCR to reduce [Ru(NH(3))(6)](3+) to detect Hg(2+) at the biocathode. It is noteworthy that this biosensor not only realizes Pb(2+) or Hg(2+) detection in a single-electrode, respectively, but also can quasi-simultaneously detect both Pb(2+) and Hg(2+) in the bioanode and the biocathode. The novel self-powered biosensor identifies Pb(2+) in the range of 10(6) fM to 10 fM with a limit of detection (LOD) of 3.1 fM and Hg(2+) in the range of 10(6) fM to 1 fM with an LOD of 0.33 fM.