(Georgia Institute of Technology, 2020-12)
Butler, James H.
Biofilms are a specialized structural formation that some bacterial species form when growing in certain environments. One such environment is the human lung, where the bacteria Pseudomonas aeruginosa forms biofilms that infect the lungs of cystic fibrosis patients. Techniques used to destroy biofilms have been studied previously, and one promising technique involves the use of bacteriophage. Phage are small, bacteria-targeting viruses that when introduced to biofilms cause the lysis, or destruction of bacterial cells and in some cases, the subsequent destruction of the biofilm. While the impact of phages on biofilms is well known, the changes in physical properties such as extracellular polymeric substance (EPS) distribution and pH distribution in biofilms treated with phage has not been examined in detail. This study seeks to establish pH distribution in Pseudomonas aeruginosa biofilms using confocal microscopy and the pH sensitive molecular probe CSNARF4, as well as SYPRO ruby biofilm for the staining of all EPS proteins. Both phage-treated and untreated biofilm samples with the separately added stains of CSNARF4 and SYPRO ruby biofilm matrix were imaged using confocal microscopy and evaluated with a microtiter plate reader, respectively. It was discovered that biofilms treated with phage exhibited little reduction in average pH across all depths into the biofilm, while there was a pronounced increase in protein release into the EPS upon cell death. These results provide greater insight into the effect phages have when being used to treat biofilms and elucidates points of improvement in biofilm treatment.
(Georgia Institute of Technology, 2019-05)
Keate, Rebecca
Cell adhesion is the fundamental process underlying all basic life processes. While structures that enhance cell adhesion strength, such as focal adhesions, have been widely characterized, influences decreasing cell adhesion strength have yet to be explored. Hyaluronan (HA), a ubiquitous polymer in extracellular matrices, is hypothesized to physically repulse cells from surfaces. Increased and specific production of HA has been recorded during events such as cell migration, cell proliferation, and tumor metastasis, which indicate HA may play a critical role in increasing cell motility. The primary objective of this work is to quantify the physical influence of HA polymers on cell adhesion strength. Using a hydrodynamic spinning disc assay, average cell adhesion strength will be quantified for various cell types, including rat chondrocytes and prostate cancer cells, in both the presence and absence HA. A more comprehensive understanding of factors influencing cell adhesion dynamics may elucidate targets for new therapeutic approaches for diseases such as cancer. The results of this study demonstrate that following HA removal, cell adhesion strength increases, and FA area does not significantly increase. This demonstrates that HA does play a significant role in influencing cell adhesion strength in both physiological and pathophysiological systems. Therefore, HA may be a potent target for future therapeutics in diseases that involve cell adhesion dysregulation.