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Rapid E.coli Detection Using Thickness Shear Mode (TSM) Biosensors

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Title: Rapid E.coli Detection Using Thickness Shear Mode (TSM) Biosensors
Author: Tao, Tao
Department: School of Engineering
Program: Engineering
Advisor: McBean, Edward Jr
Abstract: This thesis focuses on the development and improvement of fast pathogen detection methods involving TSM biosensors. The approaches introduced in this thesis consist of two main parts. The first part involves two constructed TSM biosensors, which are used for pathogen detection based on density and viscosity change of the test media along with the growth of E.coli. This thesis attempts to optimize the test media and determine the functional components affecting the oscillation frequency and shortening the initial growth phase of E.coli – the lag phase. In the lag phase, E.coli cells adjust to the ambient environment, absorb the nutrients in the test media and increase in mass, but don’t divide. The second part of the experiments is based on a constructed immunoassay TSM system. The crystals used in these experiments are coated with anti-E.coli antibodies with PCDA vesicles and gold nanoparticles. As the combination of E.coli cells and anti-E.coli antibodies leads to a mass loading on the crystal, the oscillation frequency would decrease. Therefore, this thesis explores whether the combination of E.coli and anti-E.coli antibodies can lead to a measurable frequency shift, and how the initial E.coli concentration in water samples affects the output results. This thesis concludes that a mixture of 3g/100ml mFC broth with 0.6g/100ml gelatin may be a successful test media, which has a detection limit of E.coli in the range of 1.3 ×〖10〗^4 CFU/100ml~1.333 ×〖10〗^5 CFU/100ml. In applications using this test media, the frequency shift can be up to 1800 Hz in 6 hours when E.coli concentrations reach 6.889 x 109 CFU/100ml; however, procedures to shorten the lag phase, which accounts for the majority of the entire detection time, are needed to be resolved in future research. For the constructed immunoassay TSM system, a measurable frequency shift was determined to occur only when the E.coli concentration is high enough and up to the magnitude of 107 CFU/100ml. Therefore, the approaches based on immunoassay principle need to be modified and optimized at areas of future research.
Date: 2013-07
Rights: Attribution 2.5 Canada
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Attribution 2.5 Canada Except where otherwise noted, this item's license is described as Attribution 2.5 Canada