Self-assembled DNA monolayer buffered dynamic ranges of mercuric electrochemical sensor

Anal Chem. 2013 Aug 6;85(15):7574-80. doi: 10.1021/ac401680c. Epub 2013 Jul 24.


Sensors with wide dynamic ranges (DRs) are typically constructed by utilizing a set of ligands with varied affinities for the same target. We report here a novel buffer self-assembled monolayer (BSAM) strategy, to fabricate sensors with extraordinarily broad DRs using a single recognition ligand. We demonstrated the concept of BSAM by constructing the electrochemical mercuric sensors with different surface probe densities (SPD) on a gold electrode. These sensors are based on the coordination of Hg(2+) with a pair of thymine (T) formed between the two proximate poly(T) oligonucleotides on the electrode surface and Hg(2+) binding induced DNA strand displacement of ferrocene tagged poly(A). There are three types of T-Hg(2+)-T coordination: those formed between (a) two poly(T) strands where none are hybridized with poly(A) strands, thus contributing zero effect on releasing the signaling probe, (b) poly(A)/poly(T) hybridized and nonhybridized poly(T) strands, resulting in the release of a signaling probe from the surface; and (c) two poly(A)/poly(T) hybridized strands, causing the release of two signaling probes from the surface. The DRs from 10 pM to 0.1 mM at varied SPDs were observed, attributing to the tunable Hg(2+) storage capability of the poly(T) SAM formed on the surface due to the coordination mechanism of (a) and (b). The DR was able to be further extended to 1 mM by using the longer poly(T) strands. The ready-to-use sensor exhibited great selectivity against the common interferential metal ions. As demonstrated, the BSAM strategy is a facile way to fabricate sensors with tunable and wide DRs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biosensing Techniques / methods*
  • Buffers
  • DNA Probes / chemistry*
  • Electric Conductivity
  • Electrochemistry
  • Feasibility Studies
  • Limit of Detection
  • Mercury / analysis*
  • Mercury / chemistry*
  • Nucleic Acid Hybridization
  • Surface Properties


  • Buffers
  • DNA Probes
  • Mercury