Recent Progress on the Electrochemical Biosensing of Escherichia coli O157:H7: Material and Methods Overview

Abstract

Escherichia coli O157:H7 (E. coli O157:H7) is a pathogenic strain of Escherichia coli which has issued as a public health threat because of fatal contamination of food and water. Therefore, accurate detection of pathogenic E. coli is important in environmental and food quality monitoring. In spite of their advantages and high acceptance, culture-based methods, enzyme-linked immunosorbent assays (ELISAs), polymerase chain reaction (PCR), flow cytometry, ATP bioluminescence, and solid-phase cytometry have various drawbacks, including being time-consuming, requiring trained technicians and/or specific equipment, and producing biological waste. Therefore, there is necessity for affordable, rapid, and simple approaches. Electrochemical biosensors have shown great promise for rapid food- and water-borne pathogen detection. Over the last decade, various attempts have been made to develop techniques for the rapid quantification of E. coli O157:H7. This review covers the importance of E. coli O157:H7 and recent progress (from 2015 to 2020) in the development of the sensitivity and selectivity of electrochemical sensors developed for E. coli O157:H7 using different nanomaterials, labels, and electrochemical transducers.

Keywords: E. coli O157:H7; biomedical analysis; biotechnology; electrochemical biosensors; environmental monitoring; portable biodevice.

Figure 1

(a) Schematic diagram of the fabricated steps of the electrochemical biosensor for E. coli O157:H7 using CdS@ZIF-8 as signal tags, (b) Illustration of the detection steps by DPV. (GCE, glassy carbon electrode; PABA, Poly(p-aminobenzoic acid); Ab, antibody; BSA, bovine serum albumin; Cds, cadmium sulfide quantum dots; ZIF-8, zeolitic imidazolate framework-8; PEI, polyethyleneimine; WE, working electrode; RE, reference electrode; CE, counter electrode; HCL, hydrochloric acid; DPV, differential pulse voltammetry) [59].

Figure 2

Schematic illustration of the electrochemical biosensor for E. coli O157:H7 detection. (A) Schematic illustration of the 3D DNA walker-based amplification reaction triggered by the target gene for transfer oligonucleotide fragment production; (B) Illustration of amplification reactions based on HCR and RCA on the surface of electrode to produce long double stranded DNA sequences for greater immobilization of electrochemical indicators associated with the target gene’s concentration. (Au NPs, gold nanoparticles; BN, blocking DNA; CT, circular template; DW, DNA walker; FTN, fragment of TN; H1, hairpin DNA1; H2, hairpin DNA2; H3, hairpin DNA3; HCR, hybridization chain reaction; MCH, 6-mercapto ethanol; RCA, rolling circle amplification; TN, transfer oligonucleotide) [60].

Figure 3

Schematic illustration of electrochemical cell (A) fabrication of immunosensor (B): hydroxylation (1), silanization (2), and antibody binding (3) [62].

Figure 4

Schematic illustration of the stepwise functionalization and detection of the proposed immunosensor. The black line shows the redox reaction intensity, which is inhibited as the surface covering grows. Its thickness reduction is related to decrease of the “effective” area available for the electrolyte current, which is measured through an increase of the charge transfer resistance. (I: functionalization of the surface with antibodies, II: blocking the free remaining spaces on the gold electrode by BSA, III: reaction of immobilized antibodies and the E. coli cells, IV: conveying a fresh anti-E. coli Abs solution to the circuit) [73].

Figure 5

Schematic illustration of the experimental setup of the immunosensor [77].

Figure 6

A schematic diagram of the preparation process of Ab-Fe₃O₄@SiO₂ NPs (A), Au@Pt NPs (B), Ab/invertase-Au@Pt/SiO₂ NPs (C); Experimental process of E. coli O157:H7 detection employing Ab-Fe₃O₄@SiO₂ NPs and Ab/invertase-Au@Pt/SiO₂ NPs based on PGM (D) [76].

Figure 7

Schematic illustration of the nanofiber-light addressable potentiometric sensor (NF-LAPS) sensor comprising a three-electrode system [86].