Date of Award
Doctor of Philosophy (PhD)
In the pursuit of advanced functional materials that can perform well in next-generation applications, photoredox-enabled materials constructed to harness visible and near-infrared light to control release of cargo through the manipulation of electrostatic properties can fill a gap not presently occupied to a great extent in the field. Viologens possess redox and electrostatic properties that make them uniquely suited to serve well in this space when integrated into advanced materials including hydrogels and microparticles. The counteranions commonly associated with viologens, which are typically 4,4’-dialkyl bipyridinium salts, have long been used to take advantage of solubility, synthesis, and purification. These anions can be readily exchanged via metathesis to electrostatically bind anions beyond those used to manipulate solubility, namely functional molecular cargo like anionic dyes, antibiotics, and monomer molecules among others. The metathesis and subsequent release of these more functional viologen anions through on-demand reduction of the viologen subunit has not been thoroughly investigated. To investigate electrostatic-based loading and photoredox-based release of negatively charged molecular cargo from oligoviologen-based materials and the associated kinetics of release, we sought out a new microparticle platform (Chapter 2). After numerous iterations, a water-in-oil emulsion polymerization was utilized. A methyl orange dye anion was then electrostatically loaded and released on command through a photo-induced electron transfer (PET) process with an integrated porphyrin photocatalyst. The kinetics of release from the oligoviologen-based microparticle platform were investigated through UV-Vis spectroscopic analysis. Next, this microparticle platform was loaded with anionic norbornene monomer cargo (Chapter 3) in order to investigate how release of monomer from this platform could affect polymerization kinetics using ring-opening metathesis polymerization (ROMP). To demonstrate that electrostatic-based loading and release of molecular cargo can be effective in materials of multiple length scales and to pursue biologically relevant applications, oligoviologen-crosslinked hydrogels were synthesized with an incorporated Aza-BODIPY crosslinker photocatalyst (Chapter 4). The BODIPY catalyst facilitated better access to biologically relevant red and near-IR wavelengths that can better penetrate tissue compared to blue light. The hydrogels were loaded, and their release kinetics were studied using methyl orange anion. Their effectiveness as a drug release platform was evaluated through the loading and release of antibiotic cargo to inhibit bacterial growth.
Chair and Committee
Kevin Moeller, Timothy Wencewicz, Vladimir Birman, Moe Mahjoub,
Palmquist, Mark Steven, "Electrostatic Loading and Photoredox-Driven Release of Functional Cargo from Oligoviologen-Based Materials" (2023). Arts & Sciences Electronic Theses and Dissertations. 2901.
Available for download on Friday, May 24, 2024