BioE Home

BIOE Undergraduate Honors Thesis Defenses 2017

The page below includes defense announcements for Metecan Erdi, Natalie LivingstonSonya WilliamsJessica Yau

Metecan Erdi

Friday, April 20th, 9:00am
2113A Chemical & Nuclear Engineering Building

Committee:

Dr. Peter Kofinas
Dr. Giuliano Scarcelli
Dr. Chunsheng Wang

Solid Polymer Electrolytes for Lithium and Lithium-Ion Batteries in Medical Devices

Batteries play a significant role in the overall safety, performance, and reliability of numerous life-saving and life-sustaining medical devices. Pacemakers, implantable cardioverter defibrillators, and glucose meters are characteristic examples of medical devices often subject to battery complications, including premature failure and thermal runaway. Since 2007, there have been over 19,000 self-reported cases of “battery issues” along the spectrum of medical devices according to a self-reported FDA database. Such incidents stem from the use of carbonate-based, liquid electrolyte mediums as Li+ mediators that lack both the electrochemical performance and mechanical robustness needed by commercial applications. Various combinations of ionic liquid (IL), lithium salt, and polymer matrix were blended together to form a solid polymer electrolyte (SPE) that meets both minimum safety and performance thresholds. SPEs alleviate safety concerns presented by volatile liquid electrolytes with the introduction of solid-state polymers like poly(ethylene oxide) (PEO), while the addition of tri-ethyl sulfonium bis(trifluorosulfonyl) imide (S2TFSI) IL and lithium TFSI (LiTFSI) salt, enhance ionic conductivity and ability to efficiently perform numerous charge/discharge cycles. From this particular set of components, two classes of SPEs were derived: 1) an air-stable SPE (ASPE) capable of benchtop fabrication and 2) an ionic liquid SPE (IL-SPE) sensitive to atmospheric water content. To quantify the efficacy of both systems as safer alternatives to liquid electrolytes, tests including impedance spectroscopy, linear sweep and cyclic voltammetry, galvanostatic cycling, and dynamic mechanical analysis were performed. Ultimately, two sets of novel, solid electrolyte compositions were characterized, both of which have the potential to efficiently and safely power battery systems in future medical devices.

Natalie Livingston

Wednesday, April 18th, 9:00am
1111 Jeong H. Kim Engineering Building

Committee:

Dr. Steven Jay
Dr. John Fisher
Dr. Gregory Payne

Engineering Extracellular Vesicles for Breast Cancer Therapy

RNA interference (RNAi) is a promising concept in cancer therapy, but translation has been hindered due to delivery limitations. Current successful vectors include lipid and polymeric nanoparticles as well as viral vectors, but these vehicles have limitations in vivo, including immunogenicity, toxicity, and acquired resistance. An attractive alternative delivery approach involves extracellular vesicles (EVs). EVs, which include exosomes, have been reported to have tropism for cancer cells, which may enable cancer cell-specific delivery. Here, we developed several loading methods for a variety of EV RNAi therapeutics for application in breast cancer. The first method is sonoporation, which we show here to be a viable and efficient method to load HER2 siRNA into EVs in order to knockdown the HER2 oncogene. The second method is protonation, which changes the EV interior to be acidic, therefore minimizing the loading burden of getting basic, negatively charged nucleic acids across the negatively charged EV membrane. We show here that miR-182 can be effectively delivered by protonated EVs to inhibit cell migration. The third method to promote facile loading was to incorporate cationic lipids into the EV membrane so that EVs would form a charge-based complex with RNAi molecules; however, none of the methods of incorporation chosen here showed positive results. In addition to developing loading methods, we also examined the effects of endogenous cargo in EVs isolated from cancer cells. Endogenous lncRNA HOTAIR, found in high concentrations in MBA-MD231-derived EVs, has a significant effect in cancer cell proliferation. These results show the importance of considering the source of EVs and prompt future investigation into the effect of loading methods on endogenous cargo. All together, these studies help push EV-RNAi therapies closer to the clinic.

Sonya Williams

Friday, April 13th, 12:00pm
1105 Jeong H. Kim Engineering Building

Committee:

Dr. Steven Jay
Dr. Kimberly Stroka
Dr. Edward Eisenstein

Investigating Molecular Configuration and Hexavalency to Enhance HER3 Affibody Efficacy for Targeted Cancer Therapy

The overexpression and activation of the HER3 receptor, a member of the epidermal growth factor receptor family, mediates drug resistance and disease progression in lung, breast, ovarian and prostate cancers. Currently, no HER3 targeted therapy has been FDA approved. We have previously shown that an engineered multivalent HER3 affibody has enhanced ability to block HER3 phosphorylation and downregulate HER3 receptors compared to the monovalent version of the same affibody. We hypothesized that extending these ligands to higher orders of valency could further improve therapeutic impact. In this work, we explored the potential of a novel hexavalent non-covalently associated protein configuration (HEX) consisting of six affibody domains, with the potential for increased avidity and decreased steric hindrance that might be associated with a linear molecular configuration. We examined the bioactivity of HEX configuration affibodies in comparison to a hexavalent linear affibodies and first generation bivalent affibodies.

The HEX monomers were developed using a Gibson assembly strategy. E. coli were transformed and expressed, then purified using ionized metal ion affinity chromatography and high performance liquid chromatography. Downregulation of HER3 and phosphorylated HER3 and Akt were assessed by in ovarian cancer cells (OvCAR8) via immunoblot. Comparison of the novel hexavalent protein configurations showed dose-dependent HER3 downregulation, as did the HEX linear and bivalent affibody configurations. There was no significant improvement of HER3 downregulation or inhibition of pAkt or pHER3 when cells were treated with hexavalent configurations as compared to the bivalent configuration.

While hexavalent configurations do not show improved ability to downregulate HER3, this work provides crucial data towards the optimization of HER3 ligand valency and molecular configuration. Future work will investigate optimized formats of bivalent affibodies in combination and conjugate approaches to further enhance efficacy of our overall approach that may be beneficial to the further improvement of therapeutic efficacy beyond HER3 cancer therapy.

Jessica Yau

Wednesday, April 18th, 1:00pm
1105 Jeong H. Kim Engineering Building

Committee:

Dr. Christopher Jewell
Dr. Kimberly Stroka
Dr. Steven Jay

Tunable Release of Metabolic Modulators to Restrain Autoimmune Reactions

Autoimmune diseases occur when the immune system mistakenly attacks its own cells and tissues. Multiple sclerosis (MS) is an autoimmune disease where myelin, which insulates neurons, is attacked by autoinflammatory T-cells that leads to neuronal degeneration. Dendritic cells (DCs) initiate the adaptive immune response by presenting antigens to T-cells and providing co-stimulation and cytokines, causing T-cells to proliferate and differentiate. The relative levels of co-stimulatory proteins expressed and balance of inflammatory or regulatory cytokines during the priming of a T-cell determine whether T-cells are polarized toward inflammatory or suppressive phenotypes. TREGs can suppress autoimmune reactions. Therefore, generating TREGs is a strategy for effective MS treatments. Glutamate signaling through metabotropic glutamate receptor 4 (mGluR4) can modulate the inflammatory function of DCs, promoting differentiation of TREGs.N-Phenyl-7-(hydroxyimino) cyclopropa[b] chromen-1a-carboxamide (PHCCC), a small molecule enhancer targeting mGluR4, is beneficial in experimental autoimmune encephalomyelitis (EAE), a mouse model of MS, when delivered systemically. However, PHCCC has poor solubility, displays dose limiting toxicity, and requires frequent delivery to sustain protection in EAE. Recent studies showed that at the same treatment frequency, controlled release from biodegradable PLGA NPs encapsulating PHCCC restrained symptoms of EAE while soluble PHCCC had no effect on EAE. However, treatment frequency was only decreased to every 3 days. We hypothesized that encapsulating PHCCC into different degradable polymers (e.g. poly(lactic-co-glycolic acid) (PLGA), poly(beta-amino esters) (PBAE), polycaprolactone (PCL)), would allow tuning of release kinetics and optimization of efficacy, while allowing reduced treatment frequency. We found PHCCC-loaded NPs formulated with these different polymers exhibited distinct release kinetics and modulated DC cytokine secretion. Future studies will test the ability of these NPs to promote TREGs in vivo.