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Disruption of bacterial spores using microwaves and nanoparticles

Malyshev, Dmitry 2018. Disruption of bacterial spores using microwaves and nanoparticles. PhD Thesis, Cardiff University.
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Abstract

This thesis shows how microwaves and nanoparticles can be used to enhance the disruption of spores in the context of a novel microwave-based bacterial detector. Infections linked to Clostridium difficile are a significant cause of suffering. In hospitals, the organism is primarily acquired through the faecal-oral route as spores excreted by infected patients contaminate the healthcare environment. Microwave-based spore disruption is the focus of this project offers a potential rapid diagnostic method to detect spores, including C. difficile spores by making them release DNA which is then detected. One of the limiting factors of this method was the power required and it was hypothesised that by using a new microwave cavity and adding nanoparticles, the DNA release from spores can be achieved with less power. First, the spore surface properties of the different isolates of C. difficile were compared. A significant variation in both spore morphology and spore hydrophobicity of clinical isolates of C. difficile was observed. In particular, the “pineapple-like” shape of strains was associated with higher hydrophobicity in spores, while the loose outer exosporium layer was associated with lower hydrophobicity. The isolates were then tested for DNA release in response to microwaving. Spores were shown to release single-stranded, but no double stranded DNA. The spores were also not visibly changed by microwave exposure, suggesting a non-destructive mechanism of disruption. To study this mechanism further, the microwave system was updated to remove overall sample heating and tested under electric fields, magnetic fields and a combination of the two. The electric field was shown to be causing the disruption of spores, field showed a positive correlation with increasing disruption. Finally, the spores with tested with microwaves and nanoparticles, where nanoparticles showed a significant improvement in two of the four tested isolates. A computer model of the spore and nanoparticle interactions was made, which offered a plausible mechanism for the nature of microwave mediated disruption and the improvement in disruption caused by nanoparticles.

Item Type: Thesis (PhD)
Date Type: Completion
Status: Unpublished
Schools: Pharmacy
Subjects: Q Science > Q Science (General)
Uncontrolled Keywords: spores, C. difficile, electric field, microwaves, SEM, nanoparticles.
Date of First Compliant Deposit: 1 March 2019
Last Modified: 01 Mar 2019 10:22
URI: http://orca.cf.ac.uk/id/eprint/120065

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