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Biosensors 2016, 6(2), 20;

Real-Time Detection of Staphylococcus Aureus Using Whispering Gallery Mode Optical Microdisks

Department of Engineering Physics, Polytechnique Montreal, Montreal, QC, H3T 1J4, Canada
Department of Biomedical Engineering, McGill University, Montreal, QC, H3A 2B4, Canada
Physics Department, Concordia University, Montreal, QC, H4B 1R6, Canada
Author to whom correspondence should be addressed.
Academic Editor: Samuel B. Adeloju
Received: 5 March 2016 / Revised: 19 April 2016 / Accepted: 26 April 2016 / Published: 3 May 2016
(This article belongs to the Special Issue Novel Nanobiosensors for Environmental, Food and Clinical Analyses)
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Whispering Gallery Mode (WGM) microresonators have recently been studied as a means to achieve real-time label-free detection of biological targets such as virus particles, specific DNA sequences, or proteins. Due to their high quality (Q) factors, WGM resonators can be highly sensitive. A biosensor also needs to be selective, requiring proper functionalization of its surface with the appropriate ligand that will attach the biomolecule of interest. In this paper, WGM microdisks are used as biosensors for detection of Staphylococcus aureus. The microdisks are functionalized with LysK, a phage protein specific for staphylococci at the genus level. A binding event on the surface shifts the resonance peak of the microdisk resonator towards longer wavelengths. This reactive shift can be used to estimate the surface density of bacteria that bind to the surface of the resonator. The limit of detection of a microdisk with a Q-factor around 104 is on the order of 5 pg/mL, corresponding to 20 cells. No binding of Escherichia coli to the resonators is seen, supporting the specificity of the functionalization scheme. View Full-Text
Keywords: optical microdisk; surface functionalization; bacterial sensing; specific binding optical microdisk; surface functionalization; bacterial sensing; specific binding

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Ghali, H.; Chibli, H.; Nadeau, J.L.; Bianucci, P.; Peter, Y.-A. Real-Time Detection of Staphylococcus Aureus Using Whispering Gallery Mode Optical Microdisks. Biosensors 2016, 6, 20.

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