期刊
SENSORS
卷 20, 期 1, 页码 -出版社
MDPI
DOI: 10.3390/s20010274
关键词
Escherichia coli; immunosensor; electrochemical impedance spectroscopy; antibodies; photochemical immobilization technique; cyclic voltammetry
资金
- Programma Operativo Nazionale (PON) Ricerca e Innovazione 2014-2020 Dottorati innovativi con caratterizzazione industriale
- Progetto MultiPath-Multiplex nanostructured platform for label-free detection of foodborne pathogens and carcinogenic pesticides - POR FESR CAMPANIA 2014/2020-O.S. 1.1-Avviso pubblico progetti di trasferimento tecnologico e di prima industrializzazione p
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)(6)(3-)/Fe(CN)(6)(4-) as redox probe. The Nyquist plots can be modelled with a modified Randles circuit, identifying the charge transfer resistance R-ct 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 x 10(1) 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 R-ct in terms of the effective electrode, which is modified by the detection of the analyte whose microscopic conducting properties can be quantified.
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