Single cell immunodetection of Escherichia coli O157:H7 on an indium-tin-oxide electrode by using an electrochemical label with an organic-inorganic nanostructure

Abstract

A rapid and highly sensitive method is described for the detection of enterohemorrhagic Escherichia coli O157:H7. An organic-inorganic nanostructure in which numerous gold nanoparticles (AuNPs) are enclosed with polyaniline (PANI) was utilized as an electrochemical label. The nanostructure showed (a) strong light scattering intensity due to the coupling effect of the surface plasmon resonance based on the presence of AuNPs, and (b) high electrochemical response due to the redox activity of PANI. To achieve selectivity, antibody against E. coli O157:H7 was immobilized on the surface of the nanostructure. The method exploits the combination of strong adsorption of bacterial cells onto the indium-tin-oxide (ITO) glass electrode without any special processing and specific binding of the nanostructured label to E. coli O157:H7. This enables the electrochemical detection of a single cell on the ITO electrode. The electrochemical response to E. coli O157:H7 was 30-fold higher than that to other types of bacteria. This procedure can be applied to the determination of E. coli O157:H7 even in the presence of other bacteria. Graphical abstract Schematic of a voltammetric immunoassay for Escherichia coli O157:H7 by using a nanocomposite consisting of gold nanoparticles and polyaniline on an ITO electrode.

Development of Metal Nanoparticle-immobilized Microplate for High-throughput and Highly Sensitive Fluorescence Analysis

“…E. coli O157 detection was carried out after adding 10 3 -10 6 cells of E. coli O157 to the sample solution (Table 1). 29 Recoveries of 100.6-102.4% were obtained, and the RSDs for all cases were less than 4.0%. These results reveal the feasibility of using Ag NP-immobilized plates in the detection of E. coli O157.…”

“…FITC-labeled anti-E. coli O157:H7 antibodies, which were utilized for the selectivity of the target bacteria and also as the fluorescent source, 28,29 modified the surface of the bacteria as described in Scheme 1.…”

Rapid detection of single viable Escherichia coli O157:H7 cells in milk by flow cytometry

“…A variety of technologies, such as PCR‐based methods, fluorescent aptasensing methods, and electrochemical biosensing methods, can achieve single E coli O157:H7 cell detection (Chen et al, ; Feng et al, ; Nguyen et al, ). Unfortunately, the electrochemical biosensing method cannot be used for viable cells, unlike the FCM‐based method, which can distinguish viable cells from nonviable cells (Nguyen et al, ). PCR‐based methods require approximately 10 hr in total, including 6 hr of enrichment, DNA extraction, propidium monoazide (PMA)‐treatment, PCR amplification, and agarose gel electrophoresis (Feng et al, ).…”

“…Although the traditional plate‐based method for the detection of E coli O157:H7 has a single‐cell detection limit, this method is time‐consuming, and the associated time to results (TTR) is too long, ranging from 48 to 56 hr (Buzatu et al, ). Therefore, a variety of rapid methods have been developed to replace plate‐based method, such as polymerase chain reaction (PCR) (Feng et al, ), fluorescent aptasensing (Chen et al, ), electrochemical biosensors (Nguyen, Ishik, & Shiigi, ), and flow cytometry (FCM) (Williams et al, ). However, the TTRs for PCR‐based method and the fluorescent aptasensing method are greater than 9.5 hr for single E coli O157:H7 cells, with a detection limit of only 1 cell/mL (Chen et al, ; Feng et al, ).…”

Development of highly sensitive optical nanoantenna for bacterial detection

“…The anti- E. coli O26 antibody (1.0 mg mL −1 ) was added to an aqueous 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC, 10 mg mL −1 ) solution and the mixture was stirred for 30 min. 25 The two mixtures obtained above were mixed and stirred for 2 h. The mixture was centrifuged at 6790 g and 278 K for 20 min. The supernatant was discarded, and the precipitate was dispersed in 1.0 mL of ultrapure water.…”