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BioMed Research International
Volume 2013 (2013), Article ID 640163, 6 pages
http://dx.doi.org/10.1155/2013/640163
Research Article

An Internalin A Probe-Based Genosensor for Listeria monocytogenes Detection and Differentiation

Department of Biomedical Sciences, Section of Microbiology, University of Cagliari, via Porcell 4, 09124 Cagliari, Italy

Received 19 December 2012; Revised 13 February 2013; Accepted 22 February 2013

Academic Editor: Dimitrios Karpouzas

Copyright © 2013 Laura Bifulco et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Internalin A (InlA), a protein required for Listeria monocytogenes virulence, is encoded by the inlA gene, which is only found in pathogenic strains of this genus. One of the best ways to detect and confirm the pathogenicity of the strain is the detection of one of the virulence factors produced by the microorganism. This paper focuses on the design of an electrochemical genosensor used to detect the inlA gene in Listeria strains without labelling the target DNA. The electrochemical sensor was obtained by immobilising an inlA gene probe (single-stranded oligonucleotide) on the surfaces of screen-printed gold electrodes (Au-SPEs) by means of a mercaptan-activated self-assembled monolayer (SAM). The hybridisation reaction occurring on the electrode surface was electrochemically transduced by differential pulse voltammetry (DPV) using methylene blue (MB) as an indicator. The covalently immobilised single-stranded DNA was able to selectively hybridise to its complementary DNA sequences in solution to form double-stranded DNA on the gold surface. A significant decrease of the peak current of the voltammogram (DPV) upon hybridisation of immobilised ssDNA was recorded. Whole DNA samples of L. monocytogenes strains could be discriminated from other nonpathogenic Listeria species DNA with the inlA gene DNA probe genosensor.