Nanoscience and Microsystems ETDs

Publication Date

1-28-2015

Abstract

Compounds based on the p-phenylene ethynylene backbone with pendant charged groups, known as conjugated polyelectrolytes, have been of particular interest in recent years due to their solubility in water, sensing properties, and biocidal activity against bacteria, viruses, and fungi. A series of oligomers based on these polymers were synthesized (OPEs), and several interesting questions about their photophysical and biocidal properties were raised by earlier experimental observations, which are addressed by this dissertation. The study initially focuses on the influence of the backbone length and presence of carboxyester substituents on the photophysical properties of the OPEs. Next, the photochemistry of the OPEs is explored as the products and mechanisms are elucidated through isotopic studies with mass spectrometry, revealing that photo-protonation by water and addition of oxygen across the triple bond are the two dominant initial mechanisms of all major pathways in aqueous solution. Finally, the aggregation of OPEs with is studied in two systems: surfactants and model bacterial membranes. The placement of the ionic alkyl substituents played a dominant role in determining the outcome of molecular interactions and type of aggregates which resulted between OPEs and both systems. Biophysical simulations of the interactions between OPEs and these two systems provided mechanistic insight into the mechanism of bacterial membrane disruption and the attenuation of photodegradation observed with OPE-surfactant complexes. In addition to determining the OPEs could be protected from photolysis and the structural basis for aggregate type, surfactant complexation was used to form a biocidal complex from a non-biocidal anionic OPE. The work presented will be of great use for future developments in sensors, biocides, photo-resistant materials, and drug delivery applications.

Keywords

Antimicrobial, Cell Membranes, Colloids, Molecular Dynamics, Sensors, Surfactants

Sponsors

United States Defense Threat Reduction Agency, United States National Science Foundation, United States Department of Education, University of New Mexico Office of Graduate Studies, University of New Mexico Department of Chemistry and Chemical Biology

Document Type

Dissertation

Language

English

Degree Name

Nanoscience and Microsystems

Level of Degree

Doctoral

Department Name

Nanoscience and Microsystems

First Advisor

Whitten, David G.

First Committee Member (Chair)

Deborah, Evans G.

Second Committee Member

Schanze, Kirk S.

Third Committee Member

Shreve, Andrew P.

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