Screen Printed Based Impedimetric Immunosensor for Rapid Detection of Escherichia coli in Drinking Water

Abstract

The development of a simple and low cost electrochemical impedance immunosensor based on screen printed gold electrode for rapid detection of Escherichia coli in water is reported. The immunosensor is fabricated by immobilizing anti-E. coli antibodies onto a gold surface in a covalent way by the photochemical immobilization technique, a simple procedure able to bind antibodies upright onto gold surfaces. Impedance spectra are recorded in 0.01 M phosphate buffer solution (PBS) containing 10 mM Fe(CN)63−/Fe(CN)64− as redox probe. The Nyquist plots can be modelled with a modified Randles circuit, identifying the charge transfer resistance Rct as the relevant parameter after the immobilization of antibodies, the blocking with BSA and the binding of E. coli. The introduction of a standard amplification procedure leads to a significant enhancement of the impedance increase, which allows one to measure E. coli in drinking water with a limit of detection of 3 × 101 CFU mL−1 while preserving the rapidity of the method that requires only 1 h to provide a “yes/no” response. Additionally, by applying the Langmuir adsorption model, we are able to describe the change of Rct in terms of the “effective” electrode, which is modified by the detection of the analyte whose microscopic conducting properties can be quantified.

Core-Shell Magnetic Nanoparticles for Highly Sensitive Magnetoelastic Immunosensor

“…Depending on the type of transducers, biosensors are classified in electrochemical [ 6 , 7 ], optical [ 8 , 9 ] and acoustic-wave biosensors [ 10 , 11 ]. Recently, among the magnetic biosensors [ 12 , 13 , 14 ], magnetoelastic materials (ME) have emerged as interesting acoustic-wave transducers for development of high-sensitive biosensors [ 15 ].…”

Screen-Printed Electrode-Based Sensors for Food Spoilage Control: Bacteria and Biogenic Amines Detection

“…Among the label-free sensors for E. coli detection, it is worthy to note the one recently developed by Cimafonte et al for drinking water [ 95 ]. It consisted of a sandwich-type immunosensor in which the capture antibody was immobilized with a suitable orientation on a SPAuE by a photochemical technique.…”

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

“…E. coli in drinking water was selectively and sensitively detected with a limit of detection of 3 × 10 CFU/mL. The proposed biosensor needed no preconcentration or pre-enrichment steps for the detection process [73]. The ability to perform label-free detection is the most important advantage of impedimetric electrochemical biosensors; however, in some of the conducted studies, labels have been used for signal amplification.…”

“…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].…”