SOL-GEL-DERIVED MATERIALS FOR ANTIMICROBIAL COATINGS AND ELECTROCHEMICAL NITRIC OXIDE ANALYSIS Public Deposited

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  • March 21, 2019
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  • Privett, Benjamin
    • Affiliation: College of Arts and Sciences, Department of Chemistry
Abstract
  • Sol-gel-derived coatings modified to release nitric oxide (NO), an endogenous broad-spectrum antimicrobial, have been described as highly promising antimicrobial biomaterials. As part of my thesis work, I extended the study of the antimicrobial properties of NO-releasing xerogels against the adhesion, viability, and biofilm formation of the pathogenic fungus, Candida albicans. Nitric oxide fluxes as low as 14 pmol cm-2 s-1 proved sufficient to reduce fungal adhesion by ~49% over controls (non-NO-releasing substrates) after 90 min of exposure. By utilizing a fluorescence live/dead assay and replicate plating, the NO flux was determined to reduce fungal viability in a dose dependent manner. Likewise, the formation of C. albicans biofilms on NO-releasing xerogel-coated silicon rubber (SiR) coupons was impeded when compared to control and bare SiR surfaces. To begin an examination of the likelihood of exogenous NO fostering NO resistance, bacteria were exposed to NO in long- and short-term mutagenesis assays. Even after 20 d of continuous sub-therapeutic exposure, resistance to NO was not observed for gram-positive and -negative species. The next phase of my research thus focused on the synthesis of superhydrophobic xerogel coatings from a mixture of nanostructured fluorinated silica colloids, fluoroalkoxysilane, and a backbone silane. Quantitative bacterial adhesion studies performed using a parallel plate flow cell demonstrated that the adhesion of Staphylococcus aureus and Pseudomonas aeruginosa were reduced by 2.08 ± 0.25 and 1.76 ± 0.12 log over controls, respectively. The straightforward and mild synthesis of this chemistry enables its application to any surface regardless of geometry making such interfaces ideal as biopassivation strategies. Along with NO's ability to serve a potent exogenous antimicrobial, endogenous NO serves many important physiological roles (e.g., immune response, vasodilatation, neurotransmission). The final phase of my dissertation research focused on the development of microfluidic NO sensors capable of selectively measuring NO in small volumes (<1 mL). The final device enabled sensitive NO detection in PBS, blood, and simulated wound fluid at concentrations as low as 0.7-2.0 nM. Future studies using this device may prove useful clinically.
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  • In Copyright
Advisor
  • Wightman, R. Mark
Degree
  • Doctor of Philosophy
Graduation year
  • 2011
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