Conductometric Immunosensor for Escherichia coli O157:H7 Detection Based on Polyaniline/Zinc Oxide (PANI/ZnO) Nanocomposite.

Sawsan Mutlaq,Mutamed M Ayyash,Borhan Albiss,Mohammad S Khalifeh,Tareq Osaili,Amin N Olaimat,Ziad W Jaradat,Anas A Al-Nabulsi,Richard A Holley

doi:10.3390/polym13193288

Abstract

A conductometric immunosensor was developed for the detection of one of the most common foodborne pathogens, Escherichia coli O157:H7 (E. coli O157:H7), by conductometric sensing. The sensor was built based on a polyaniline/zinc oxide (PANI/ZnO) nanocomposite film spin-coated on a gold electrode. Then, it was modified with a monoclonal anti-E. coli O157:H7 antibody as a biorecognition element. The fabricated nanostructured sensor was able to quantify the pathogens under optimal detection conditions, within 30 min, and showed a good detection range from 101 to 104 CFU/mL for E. coli O157:H7 and a minimum detection limit of 4.8 CFU/mL in 0.1% peptone water. The sensor efficiency for detecting bacteria in food matrices was tested in ultra-heat-treated (UHT) skim milk. E. coli O157:H7 was detected at concentrations of 101 to 104 CFU/mL with a minimum detection limit of 13.9 CFU/mL. The novel sensor was simple, fast, highly sensitive with excellent specificity, and it had the potential for rapid sample processing. Moreover, this unique technique for bacterial detection could be applicable for food safety and quality control in the food sector as it offers highly reliable results and is able to quantify the target bacterium.

Highlights

The increase in sensor electrical conductivity can be related to an increase in antigen-antibody immune-complex formation on the electrode surface, which interrupted the electrical flow in the electrode [17,36,37]
A PANI/zinc oxide (ZnO) nanocomposite film was prepared and used to develo nanostructured immunosensor for the detection of E. coli O157:H7 based on antibo antigen interaction
The enhanced electrical conductivity of the PANI/ZnO nanocom site increased the sensitivity of E. coli O157:H7 detection

Summary

Introduction

Escherichia coli O157:H7 is one of the most common foodborne bacterial pathogens and it belongs to the enterohemorrhagic E. coli (EHEC) group [2,3]. This bacterium is mainly found in the gut of cattle as its main reservoir [4,5]. The incidence of foodborne illness associated with E. coli O157:H7 is low compared to other pathogenic bacteria, it can cause severe symptoms and life-threatening illnesses such as hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS), which can lead to kidney failure if not treated [4,6]. It is urgent that an effective and rapid technique be developed to detect E. coli O157:H7 in food products throughout the production and distribution chain

Methods

Results

Conclusion