Abstract

The development of a selective and sensitive electrochemical DNA biosensor for detection of the
pathogen Bacillus anthracis is proposed here. The technique is based on the characteristic cyclic
voltammetry (CV) redox peaks and the very selective nature of DNA hybridization. The designed
system consists of a self-assembled layer of mercaptohexanol (MCH) and thiol linked probe (ssDNAthiol)
immobilized on gold-modified screen-printed electrodes. This direct detection technique studies
the change in potential and intensity of the surface-modified screen-printed electrodes when a 5mM
Fe(CN)6
3-
solution in 0.1M KClis presented to the electrodic system in the range between -0.5 to 0.7V.
The increase or decrease in the electron transfer along with the varied redox potential during
immobilization of the probe and hybridization of the target was observed as CV peak current and
potential change. The proposed system showed reliable results with sensitivity up to 10pM and
selective enough to distinguish signals from DNA fragments presenting 1bp mismatches. The
fabricated system with the thiol probe once produced could be shelved for 2-3 months.Thus the strong
selective binding nature of the DNA along with the sensitive CV characters, prove to be an efficient
system for reliable detection of pathogens.