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Open AccessArticle

Selective Uropathogenic E. coli Detection Using Crossed Surface-Relief Gratings

1
Department of Chemical Engineering, Queen’s University, Kingston, ON K7L 3N6, Canada
2
Instituto de Ciencias Aplicadas y Desarrollo Tecnológico (ICAT), Universidad Nacional Autónoma de México (UNAM), Ciudad de México 04510, Mexico
3
Departamento de Salud Pública, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), Ciudad de México 04510, Mexico
4
Unidad Periférica de Patogénesis Bacteriana en Hospital General Dr. Manuel Gea González, Ciudad de México 14080, Mexico
5
Department of Physics and Space Science, Royal Military College of Canada, Kingston, ON K7K 7B4, Canada
*
Authors to whom correspondence should be addressed.
These authors contributed equally to this work.
Sensors 2018, 18(11), 3634; https://doi.org/10.3390/s18113634
Received: 31 August 2018 / Revised: 23 October 2018 / Accepted: 24 October 2018 / Published: 26 October 2018
(This article belongs to the Special Issue Label-free Optical Nanobiosensors)
Urinary tract infections (UTIs) are one of the major burdens on public healthcare worldwide. One of the primary causes of UTIs is the invasion of the urinary tract by uropathogenic Escherichia coli (UPEC). Improper treatment of bacterial infections like UTIs with broad-spectrum antibiotics has contributed to the rise of antimicrobial resistance, necessitating the development of an inexpensive, rapid and accurate detection of UPEC. Here, we present real-time, selective and label-free detection of UPEC using crossed surface-relief gratings (CSRGs) as nanometallic sensors incorporated into an optical sensing platform. CSRGs enable real-time sensing due to their unique surface plasmon resonance (SPR)-based light energy exchange, resulting in detection of a very-narrow-bandwidth SPR signal after the elimination of residual incident light. The platform’s sensing ability is experimentally demonstrated by the detection of bulk refractive index (RI) changes, with a bulk sensitivity of 382.2 nm/RIU and a resolution in the order of 10−6 RIU. We also demonstrate, for the first time, CSRG-based real-time selective capture and detection of UPEC in phosphate-buffered saline (PBS) solution, in clinically relevant concentrations, as opposed to other UTI-causing Gram-negative bacteria. The platform’s detection limit is calculated to be 105 CFU/mL (concentration on par with the clinical threshold for UTI diagnosis), with a dynamic range spanning four orders of magnitude. This work paves the way for the development of inexpensive point-of-care diagnosis devices focusing on effective treatment of UTIs, which are a burden on public healthcare due to the rise in the number of cases and their recurrences in the recent past. View Full-Text
Keywords: surface plasmon resonance; urinary tract infection; surface-relief gratings; crossed surface-relief gratings; nanoplasmonics; biosensing; uropathogenic E. coli surface plasmon resonance; urinary tract infection; surface-relief gratings; crossed surface-relief gratings; nanoplasmonics; biosensing; uropathogenic E. coli
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Nair, S.; Gomez-Cruz, J.; Manjarrez-Hernandez, Á.; Ascanio, G.; Sabat, R.G.; Escobedo, C. Selective Uropathogenic E. coli Detection Using Crossed Surface-Relief Gratings. Sensors 2018, 18, 3634.

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