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Title: Early-stage adhesion of microbes onto oral biomaterials at the nanoscale
Author: Aguayo Paul, S. D.
ISNI:       0000 0004 7225 6902
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2017
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Despite much progress, the infection of oral biomaterials by bacterial and fungal cells remains an important problem in the clinic, affecting millions of patients worldwide. Although biofilm formation comprises a series of stages, the initial cell-surface interaction is crucial in determining infection of the biomaterial surface. By employing single-cell force spectroscopy (SCFS) and nanoindentation with the atomic force microscope (AFM), the biophysics of the bacteria-biomaterial surface interaction has been characterised for Streptococcus sanguinis, Staphylococcus aureus and Candida albicans. Initially, the development and optimisation of a protocol to harvest and immobilise living bacterial and fungal cells for AFM experimentation is described. In a next step, SCFS was utilised to explore the influence of implant surface nanotopography on the colonisation of S. aureus, utilising an in vitro polycarbonate implant model. Although nanotopography was not found to influence bacterial elasticity, it did increase the adhesion of S. aureus to the surface at early time points. Subsequently, the interaction between clinically relevant titanium (Ti) implant substrates and S. aureus and S. sanguinis cells was studied, which demonstrated strain-dependent differences in the unbinding patterns observed in AFM experiments. Worm-like chain (WLC) modelling of unbinding events was used to predict the length of the bacterial adhesins involved in the Ti-bacteria interaction, which were found to be different for S. aureus and S. sanguinis. Finally, the attachment of C. albicans to acrylic surfaces at the single-cell level was explored with AFM. C. albicans was found to exhibit morphology-dependent adhesion onto acrylic, with adhesion being increased in hyphal tubes compared to yeast cells. Also, experiments suggest a potential correlation between strain virulence and increased adhesion to surfaces. Future work should focus on utilising this in vitro AFM model to explore novel antiadhesive and antimicrobial approaches at the single-cell level.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available