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Open AccessArticle

Electrochemical Detection of E. coli O157:H7 in Water after Electrocatalytic and Ultraviolet Treatments Using a Polyguanine-Labeled Secondary Bead Sensor

1
Department of Mechanical Engineering, University of Utah, Salt Lake City, UT 84112, USA
2
Espira Inc., 825 N 300 W Suite N-223, Salt Lake City, UT 84103, USA
3
Department of Metallurgical Engineering, University of Utah, Salt Lake City, UT 84112, USA
4
Department of Chemical Engineering, University of Utah, Salt Lake City, UT 84112, USA
*
Authors to whom correspondence should be addressed.
Sensors 2018, 18(5), 1497; https://doi.org/10.3390/s18051497
Received: 22 March 2018 / Revised: 1 May 2018 / Accepted: 7 May 2018 / Published: 10 May 2018
(This article belongs to the Special Issue Immunosensors - 2018 Trends and Perspective)
The availability of clean drinking water is a significant problem worldwide. Many technologies exist for purifying drinking water, however, many of these methods require chemicals or use simple methods, such as boiling and filtering, which may or may not be effective in removing waterborne pathogens. Present methods for detecting pathogens in point-of-use (POU) sterilized water are typically time prohibitive or have limited ability differentiating between active and inactive cells. This work describes a rapid electrochemical sensor to differentially detect the presence of active Escherichia coli (E. coli) O157:H7 in samples that have been partially or completely sterilized using a new POU electrocatalytic water purification technology based on superradicals generated by defect laden titania (TiO2) nanotubes. The sensor was also used to detect pathogens sterilized by UV-C radiation for a comparison of different modes of cell death. The sensor utilizes immunomagnetic bead separation to isolate active bacteria by forming a sandwich assay comprised of antibody functionalized secondary magnetic beads, E. coli O157:H7, and polyguanine (polyG) oligonucleotide functionalized secondary polystyrene beads as an electrochemical tag. The assay is formed by the attachment of antibodies to active receptors on the membrane of E. coli, allowing the sensor to differentially detect viable cells. Ultravioloet (UV)-C radiation and an electrocatalytic reactor (ER) with integrated defect-laden titania nanotubes were used to examine the sensors’ performance in detecting sterilized cells under different modes of cell death. Plate counts and flow cytometry were used to quantify disinfection efficacy and cell damage. It was found that the ER treatments shredded the bacteria into multiple fragments, while UV-C treatments inactivated the bacteria but left the cell membrane mostly intact. View Full-Text
Keywords: Escherichia coli O157:H7 detection; defect laden titania (TiO2)-based reactor; biosensors; pathogen detection; electrochemical detection; square wave voltammetry; immunomagnetic separation Escherichia coli O157:H7 detection; defect laden titania (TiO2)-based reactor; biosensors; pathogen detection; electrochemical detection; square wave voltammetry; immunomagnetic separation
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Beeman, M.G.; Nze, U.C.; Sant, H.J.; Malik, H.; Mohanty, S.; Gale, B.K.; Carlson, K. Electrochemical Detection of E. coli O157:H7 in Water after Electrocatalytic and Ultraviolet Treatments Using a Polyguanine-Labeled Secondary Bead Sensor. Sensors 2018, 18, 1497.

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