Hakan Karadeniz* and Arzum Erdem Pages 1 - 9 ( 9 )
Background: Anthrax Lethal Factor (ANT) is the dominant virulence factor produced by B. anthracis and is the major cause of death of infected animals. In this paper, pencil graphite electrodes (PGE) were modified with single-walled (SW) and multi-walled (MW) carbon nanotubes (CNTs) for the detection of hybridization related to the ANT DNA for the first time in the literature. Methods: The electrochemical monitoring of label-free DNA hybridization related to ANT DNA was explored using both SWCNT and MWCNT modified PGEs with differential pulse voltammetry (DPV). The performance characteristics of ANT-DNA hybridization on disposable PGEs were explored by measuring the guanine signal in terms of optimum analytical conditions; the concentration of SWCNT and MWCNT, the concentrations of probe and target, and also the hybridization time. Under the optimum conditions, the selectivity of probe modified electrodes was tested and the detection limit was calculated. Results: The selectivity of ANT probes immobilized onto MWCNT-PGEs was tested in the presence of hybridization of probe with NC no response was observed and with MM, smaller responses were observed in comparison to full-match DNA hybridization case. Even though there are unwanted substituents in the mixture samples containing both the target and NC in the ratio 1:1 and both the target and MM in the ratio 1:1, it has been found that ANT probe immobilized CNT modified graphite sensor can also select its target by resulting with 20.9 % decreased response in comparison to the one measured in the case of full-match DNA hybridization case Therefore, it was concluded that the detection of direct DNA hybridization was performed by using MWCNT-PGEs with an acceptable selectivity. Conclusion: Disposable SWCNT/MWCNT modified PGEs bring some important advantages to our assay including easy use, cost-effectiveness and giving a response in a shorter time compared to unmodified PGE, carbon paste electrode and glassy carbon electrode developed for electrochemical monitoring of DNA hybridization. Consequently, the detection of DNA hybridization related to the ANT DNA by MWCNT modified sensors was performed by using lower CNT, probe and target concentrations, in a shorter hybridization time and resulting in a lower detection limit according to the SWCNT modified sensors. In conclusion, MWCNT modified sensors can yield the possibilities leading to the development of nucleic acid sensors platforms for the improvement of fast and costeffective detection systems with respect to DNA chip technology.
Electrochemistry; Biosensor; Anthrax Lethal Factor; DNA hybridization; Carbon nanotubes; Differential pulse voltammetry
Ege University Faculty of Pharmacy, Department of Analytical Chemistry, 35100, Bornova, Izmir, Ege University Faculty of Pharmacy Department of Analytical Chemistry, 35100, Bornova, Izmir