Sequence-specific detection of trace DNA via a junction-probe electrochemical sensor employed template-enhanced hybridization strategy

A novel junction-probe electrochemical biosensor for the sequence-specific detection of DNA with higher sensitivity and higher discrimination ability was described in here. This DNA biosensor is based on “junction-probe” detection strategy, which operates via a concept called template-enhanced hybridization processes (TeHyP). TeHyP encompasses a design strategy whereby two probes that do not hybridize to each other at a specific temperature can be made to anneal to each other in the presence of a template (target) via the formation of a ternary complex (“Y” junction structure). The resulting structure that forms after the template-enhanced hybridization then was detected by electrochemical method with [Ru(NH3)6]3+ as signal molecule. We demonstrated that the formation of “Y” junction structure brings more [Ru(NH3)6]3+ to the electrode surface via electrostatic interaction and results in an increasing electrochemical signal. The increasing electrochemical signal sensitively reflects the concentration of target DNA and shows a good linear relationship with the concentration of target DNA. By employing above strategy, this DNA biosensor could detect as low as 7.6 × 10−13 M target DNA and exhibited high discrimination ability even against single-base mismatch. In addition, this novel DNA biosensor is easy to fabricate and convenient to operate, and shows good stability, reproducibility and reusability.