Single walled carbon nanotube-based junction biosensor for detection of Escherichia coli.

Kara Yamada,Hyeon Gyu Lee,Jae-Hyun Chung,Jong-Hoon Kim,Chong-Tai Kim,Soojin Jun,Aristides Docoslis

doi:10.1371/journal.pone.0105767

Abstract

Foodborne pathogen detection using biomolecules and nanomaterials may lead to platforms for rapid and simple electronic biosensing. Integration of single walled carbon nanotubes (SWCNTs) and immobilized antibodies into a disposable bio-nano combinatorial junction sensor was fabricated for detection of Escherichia coli K-12. Gold tungsten wires (50 µm diameter) coated with polyethylenimine (PEI) and SWCNTs were aligned to form a crossbar junction, which was functionalized with streptavidin and biotinylated antibodies to allow for enhanced specificity towards targeted microbes. In this study, changes in electrical current (ΔI) after bioaffinity reactions between bacterial cells (E. coli K-12) and antibodies on the SWCNT surface were monitored to evaluate the sensor's performance. The averaged ΔI increased from 33.13 nA to 290.9 nA with the presence of SWCNTs in a 108 CFU/mL concentration of E. coli, thus showing an improvement in sensing magnitude. Electrical current measurements demonstrated a linear relationship (R2 = 0.973) between the changes in current and concentrations of bacterial suspension in range of 102–105 CFU/mL. Current decreased as cell concentrations increased, due to increased bacterial resistance on the bio-nano modified surface. The detection limit of the developed sensor was 102 CFU/mL with a detection time of less than 5 min with nanotubes. Therefore, the fabricated disposable junction biosensor with a functionalized SWCNT platform shows potential for high-performance biosensing and application as a detection device for foodborne pathogens.

Highlights

The presence of pathogenic bacteria in our food and water is a major concern in the food industry because of its critical impact on public health and economy
This paper describes the development and performance of a disposable biosensor based on single walled carbon nanotubes (SWCNTs)-coated microwires assembled into a crossbar junction and immobilized with antibodies for bacterial detection
The results indicated that the network of SWCNTs enhanced the signal response by seven-folds

Summary

Introduction

The presence of pathogenic bacteria in our food and water is a major concern in the food industry because of its critical impact on public health and economy. Occurrence of foodborne illness outbreaks continues to rise as a consequence of globalized food supply, large-scale food production, and a growing population of disease susceptible consumers [1]. Non-typhoidal Salmonella spp., Listeria monocytogenes, Campylobacter spp., Escherichia coli O157:H7, Clostridium perfringens and Staphylococcus aureus are commonly found to be the source of bacterial contaminations in our food supply [2]. Illnesses related to these pathogens range in severity from nausea and diarrhea to life-threatening conditions, such as hemorrhagic colitis and hemolytic uremic syndrome caused by E. coli O157:H7

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Conclusion