Abstract

Escherichia coli O157:H7 (E. coli O157:H7) is an enterohemorrhagic E. coli (EHEC), which has been issued as a major threat to public health worldwide due to fatal contamination of water and food. Thus, its rapid and accurate detection has tremendous importance in environmental monitoring and human health. In this regard, we report a simple and sensitive electrochemical DNA biosensor by targeting Z3276 as a genetic marker in river water. The surface of the designed gold electrode was functionalized with gold nanostars and an aminated specific sensing probe of E. coli O157:H7 to fabricate the genosensor. Cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques were applied for electrochemical characterization and detection. The synthesized gold nanostars were characterized using different characterization techniques. The fabricated DNA-based sensor exhibited a high selective ability for one, two, and three-base mismatched sequences. Regeneration, stability, selectivity, and kinetics of the bioassay were investigated. Under optimal conditions, the fabricated genosensor exhibited a linear response range of 10-5 to 10-17 μM in the standard sample and 7.3 to 1 × 10-17 μM in water samples with a low limit of quantification of 0.01 zM in water samples. The detection strategy based on silver plated gold nanostars and DNA hybridization improved the sensitivity and specificity of the assay for E. coli O157:H7 detection in real water samples without filtration. The detection assay has the advantages of high selectivity, sensitivity, low amounts of reagents, short analysis time, commercialization, and potential application for the determination of other pathogenic bacteria.

Highlights

  • BPharmaceutical Analysis Research Center, Tabriz University of Medical Sciences, Tabriz 51664, Iran † Electronic supplementary information (ESI) available: Fig. S1: TEM images of AuNSs

  • There has been a noticeable increase in the integration of different nanostructures with sensors for the detection of pathogenic bacteria

  • Nucleic acids as the sensing elements pose an enormous potential for efficient detection of pathogenic bacteria

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Summary

Introduction

BPharmaceutical Analysis Research Center, Tabriz University of Medical Sciences, Tabriz 51664, Iran † Electronic supplementary information (ESI) available: Fig. S1: TEM images of AuNSs. S6: (A) SWVs of the fabricated genosensor a er hybridization in different incubation time of tDNA (10, 30 and 40 min). S9: Regeneration study: (1) SWV signal of Au-GNSs-pDNA-MCE-TB-tDNA. (2) SWV signal of Au-GNSs-pDNA-MCE-TB-tDNA a er keeping at 60 C for 3 min and a er re-hybridization.

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