Date on Master's Thesis/Doctoral Dissertation

12-2020

Document Type

Doctoral Dissertation

Degree Name

Ph. D.

Department

Chemical Engineering

Degree Program

Chemical Engineering, PhD

Committee Chair

Fried, Joel

Committee Co-Chair (if applicable)

Steinbach-Rankins, Jill

Committee Member

Steinbach-Rankins, Jill

Committee Member

Frieboes, Hermann

Committee Member

Gupta, Gatum

Committee Member

Jaeger, Vance

Committee Member

Palmer, Kenneth E.

Author's Keywords

Drug delivery; sexually transmitted infections; bacterial vaginosis

Abstract

Female reproductive viral and bacterial infections affect millions of women worldwide. Given the diversity and magnitude of these unmet reproductive health challenges, topical administration of antiretrovirals (ARVs) and antibiotics have emerged as promising approaches to maintain and restore reproductive health. However, currently available intravaginal dosage forms often suffer from low user adherence and the need for frequent, daily administration to achieve therapeutic effect. To address these challenges, the broad goal of this research was to focus on the development of new localized nanoparticle (NP) and electrospun fiber dosage forms to prolong the delivery and enhance the efficacy of active agents to treat viral and bacterial infections. The first goal of this work was to evaluate the synergistic interactions between a biologic, Q-Griffithsin (Q-GRFT), and three ARVs − tenofovir (TFV), raltegravir (RAL), and dapivirine (DAP) − in free and encapsulated forms, to identify unique protein-drug synergies to prevent human immunodeficiency virus type 1 (HIV-1) infection. Free Q-GRFT and free ARV co-administration resulted in strong synergistic interactions, relative to administration of each active agent alone. Similarly, Q-GRFT NP and ARV NP co-administration resulted in synergy across all formulations, with the most potent interactions between encapsulated Q-GRFT and DAP. This work suggests that Q-GRFT and ARV co-administration in free or encapsulated forms may improve efficacy and decrease the dose required to achieve prophylaxis. Moreover, the encapsulation of different active agents in NP-based platforms may provide modest levels of sustained-release with utility to a variety of agents and infection types. The second part of this dissertation focused on the use of molecular dynamics (MD) and molecular mechanics simulations to study the compatibility of the mentioned ARVs with PLGA NPs. Solubility parameters were calculated for water, polymer, and each drug individually, and were compared with those attained from a group-contribution method (GCM). In addition, plots of the radial distribution function (RDF) and calculated charges obtained from electrostatic potential (ESP) fitting were used to compare the interactions between each drug and the polymer. Results indicated stronger hydrogen bonding between RAL and PLGA compared to TFV and PLGA. These findings explain the experimental observation that PLGA NPs encapsulating RAL have significantly higher encapsulation efficiency relative to NPs encapsulating TFV. This result provides important insight into the role of drug–polymer interactions on the encapsulation efficacy of small molecule antiretrovirals in polymeric NPs. The third goal of this dissertation was to develop a new electrospun fiber dosage form to promote vaginal microbiota health, with the potential to prolong probiotic delivery for bacterial vaginosis (BV) treatment. First, we examined the initial safety and efficacy of fast-dissolving polyethylene oxide (PEO) fibers formulated alone or with an antibiotic in an established murine model of BV infection. We then fabricated PEO and polyvinyl alcohol (PVA) fibers containing Lactobacillus acidophilus (L. acidophilus) as a model probiotic. In addition, different parameters including electrospinning solution, the use of fresh or lyophilized bacteria, and extended storage conditions were evaluated for their impact on L. acidophilus viability and fiber morphology. Our results show that probiotics are highly and viably incorporated in PEO and PVA fibers, and exhibit prolonged stability for up to 3 months within -20 or 4°C storage conditions. In addition, this study suggests that blank and antibiotic-containing PEO fibers are safe in vivo, inert to the vaginal mucosa in the absence and presence of Gardnerella vaginalis (G. vaginalis) infection, and capable of delivering effective therapeutics. In addition, probiotics were highly and viably incorporated in PEO and PVA fibers, and exhibited prolonged stability for up to 3 months within -20 or 4°C storage conditions. Furthermore, PEO and PVA fibers inhibited the viability and cell adhesion of G. vaginalis, in both soluble and epithelial-based co-culture assays, suggesting their ability to exert health-promoting effects against pathogenic species involved in BV. Lastly, we sought to build upon the baseline hydrophilic rapid release fiber dosage form to develop a fiber-based sustained-release delivery platform to prolong probiotic release for up to 2 weeks. Two different fiber architectures – mesh and layered – were developed to incorporate two lactic acid-producing model organisms, Lactobacillus crispatus (L. crispatus) and Lactobacillus acidophilus (L. acidophilus). In this study, fiber mass loss and morphology were assessed to evaluate fiber degradation over 2 wk, followed by the assessment of probiotic release and proliferation, lactic acid release, and changes in pH. Lastly, the efficacy of these fibers was evaluated in an in vitro soluble co-culture assay against G. vaginalis infection. Both fiber architectures prolonged probiotic release for up to 14 d and produced therapeutically-relevant levels of lactic acid, which correlated with a significant reduction in pH. Moreover, probiotic-containing fibers showed similar inhibitory properties to free probiotics against G. vaginalis, indicating that probiotics maintain their activity after electrospinning and have the potential to fully inhibit G. vaginalis infection. This study demonstrated that electrospun fibers composed of both hydrophilic and hydrophobic polymers may offer a viable long-term alternative to daily administration to maintain vaginal health, treat BV, and prevent BV recurrence.

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