OligoG alginate nanomedicine mediated disruption of mucin barriers and microbial biofilms

Doctoral thesis English OPEN
Pritchard, Manon
  • Subject: Q1 | RK

Bacterial and fungal biofilms are an increasing clinical challenge, from non-healing wounds to chronic lung infections in cystic fibrosis (CF) patients. Escalating antimicrobial resistance has led to a need for alternative treatments. OligoG (a low MW alginate oligosaccharide), can disrupt multi-drug resistant bacterial biofilms and decrease antibiotic resistance.\ud This study characterised the interaction between OligoG and the most prevalent CF pathogen, Pseudomonas aeruginosa, using nanoscale characterisation, imaging and fluorescent conjugation. Further investigation into the effect of OligoG on CF sputum was carried out using Fourier transform infrared spectroscopy (FTIR) and rheology. The work was extended to observe changes in fungal pathogens treated with OligoG.\ud Electrophoretic light scattering (ELS) and dynamic light scattering revealed that the surface charge of P. aeruginosa became more negative when treated with OligoG (P<0.001) with an increase in sizing. These interactions were not disrupted by hydrodynamic shear (P<0.0001). Biofilm inhibition and disruption of a mucoid P. aeruginosa strain, treated with OligoG, was demonstrated using confocal laser scanning microscopy (P<0.05). Fluorescent conjugation to OligoG revealed its distribution throughout the biofilm.\ud In vitro scanning electron microscopy (SEM), atomic force microscopy (AFM) and ELS of mucin showed disruption in aggregation when treated with OligoG (P<0.005), with the surface charge becoming more negative (P<0.0001). Ex vivo treatment of CF sputum with OligoG analysed using FTIR and rheology, demonstrated possible interaction with the sulfate moiety of mucin and a reduction in the viscous and elastic response (0.16 Hz; P<0.0001).\ud AFM and SEM analysis of candidal biofilms treated with OligoG demonstrated a dose response in reducing biofilm formation, with a decrease in hyphal formation. An in vitro epithelial model demonstrated these changes at <2% OligoG.\ud These studies provide insight into the role of OligoG as a treatment for CF patients. Furthermore, promising results have shown that OligoG may lower candidal pathogenicity.
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