Effect of calcium phosphate topography and composition on bacterial adhesion and proliferation
Document typeMaster thesis
Rights accessRestricted access - confidentiality agreement
Recent studies have shown that certain topographies can have bactericidal properties. This project studies the adhesion and proliferation of Pseudomonas aeruginosa bacteria, one of the most common bacteria in surgical infections, in different calcium phosphates topographies to test which ones confer the best bactericidal properties. The project initiates with the obtention of calcium phosphates with six different topographies: a calcium-deficient hydroxyapatite cement with an irregular surface of microplates (C-HA); a calcium-deficient hydroxyapatite cement with an irregular nano-needle surface (F-HA); F-comp and C-comp, which possess the topographies of F-HA and C-HA respectively on a flat surface; a sintered tricalcium phosphate of porous topography formed by polyhedral grains (β-TCP); and finally a flat surface, obtained from the compaction of calcium-deficient hydroxyapatite powder (Flat-F). The intercrystalline distance and the size of the precipitated crystals are then measured to contrast, using a theoretical model, that the surface of the calcium phosphate cement F is successfully potentially bactericidal. Then different bacterial tests are performed on the different topographies. the surface covered by the adhering bacteria is analyzed using live/dead staining for confocal microscopy. The first experiments were aimed at establishing different fixation protocols with glutaraldehyde, as it improves the quality of the images obtained, but the results were not conclusive enough to ensure the reliability of any of these procedures. Finally, a bacterial incubation assay is performed on the F-HA, C-HA, β-TCP, and F-flat (ctrl) samples. The results obtained are consistent with the conclusions of the theoretical model as the F-HA topography turned out to be the most bactericidal.
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