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Antimicrobial and cleaning modes of action of peroxide and reactive oxygen species for combating biofilms

Oliveira Lourenco, Claudio; (2020) Antimicrobial and cleaning modes of action of peroxide and reactive oxygen species for combating biofilms. Doctoral thesis (Eng.D), UCL (University College London). Green open access

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Abstract

Poor denture hygiene is the underlying cause behind several undesirable effects including denture stomatitis, bad breath, staining among others. Dentures are immediately exposed to microbes and quickly become colonized by biofilm. Dentures therefore require regular cleaning and disinfection by a safe and reliable product. With this in view, the effects of reactive oxygen species (ROS) in the removal of biofilms and stains were studied. Furthermore, the kinetics of the reaction and the pH conditions necessary for effective production of reactive oxygen species within a formulation and its antibiofilm properties were also investigated. 1H-NMR was used to kinetically follow ROS production at different pH in the tetraacetylethylenediamine (TAED)/ hydrogen peroxide (H2O2) system within different formulations and complemented with fluorometric detection of ROS. Subsequently the antimicrobial properties of the tested formulations were observed against oral microorganisms in suspension and were supplemented with biofilm studies to visualize the biofilm removal properties of ROS using confocal microscopy and scanning electron microscopy. Quantitative 1H-NMR and fluorimetry proved to be robust and reliable methods to assess the efficacy of a formulation in delivering ROS. At pH 5.5, the reaction progressed more slowly but generated a higher amount of singlet oxygen while at pH 7 the initial reaction occurred slightly faster, but the generation of ROS was slower. ROS were also a key component in the removal of biofilm. When Polident was tested vs a placebo tablet it was observed that Polident not only removed biofilm but also killed nearly all of the remaining cells while placebo only managed to remove some biofilm and left many live cells. At optimal pH with only ROS as a weapon our novel formulations achieved results comparable with the denture cleanser tablet proving the excellent antimicrobial properties of ROS.

Type: Thesis (Doctoral)
Qualification: Eng.D
Title: Antimicrobial and cleaning modes of action of peroxide and reactive oxygen species for combating biofilms
Event: UCL
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Copyright © The Author 2020. Original content in this thesis is licensed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) Licence (https://creativecommons.org/licenses/by/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request.
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Chemistry
URI: https://discovery.ucl.ac.uk/id/eprint/10112700
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