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Open AccessArticle

Rapid Detection of Microorganisms Based on Active and Passive Modes of QCM

1
CEITEC MU, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic
2
Department of Biochemistry, Faculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic
*
Author to whom correspondence should be addressed.
These authors contributed equally to this work.
Sensors 2015, 15(1), 79-92; https://doi.org/10.3390/s150100079
Received: 24 October 2014 / Accepted: 11 December 2014 / Published: 23 December 2014
Label-free immunosensors are well suited for detection of microorganisms because of their fast response and reasonable sensitivity comparable to infection doses of common pathogens. Active (lever oscillator and frequency counter) and passive (impedance analyzer) modes of quartz crystal microbalance (QCM) were used and compared for rapid detection of three strains of E. coli. Different approaches for antibody immobilization were compared, the immobilization of reduced antibody using Sulfo‑SMCC was most effective achieving the limit of detection (LOD) 8 × 104 CFU·mL−1 in 10 min. For the passive mode, software evaluating impedance characteristics in real-time was developed and used. Almost the same results were achieved using both active and passive modes confirming that the sensor properties are not limited by the frequency evaluation method but mainly by affinity of the antibody. Furthermore, reference measurements were done using surface plasmon resonance. Effect of condition of cells on signal was observed showing that cells ruptured by ultrasonication provided slightly higher signal changes than intact microbes. View Full-Text
Keywords: Escherichia coli; immunosensor; impedance analysis; label-free detection; quartz crystal microbalance Escherichia coli; immunosensor; impedance analysis; label-free detection; quartz crystal microbalance
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MDPI and ACS Style

Farka, Z.; Kovář, D.; Skládal, P. Rapid Detection of Microorganisms Based on Active and Passive Modes of QCM. Sensors 2015, 15, 79-92.

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