Benzalkonium Chlorides (BACs) are widely used antimicrobial disinfectants in a variety of settings, including large scale food processing and consumer environments. Persistent usage of BACs raises concerns about the potential disruption of the gastrointestinal microbiota, an increasingly recognized regulator of an individual’s health. Furthermore, the gut microbiota has been shown to regulate drug metabolizing enzymes (DMEs) and the Gut-Liver Axis is a known prominent crosstalk pathway. Previous work in our lab has found BACs are capable of altering gut microbiome composition in BAC exposed C57BL/6 male and female mice, with notable differences between the male and female sexes. Therefore, we hypothesize that exposure to the BACs can alter the composition of gut microbiota, leading to sex specific changes in bile acid homeostasis as well as the metabolic phenotype and DME expression of the liver. In this study, we exposed male and female mice to C12- and C16-BACs at 120 ug/g/day for one week via oral dosing. Additionally, through a targeted bile acid quantitation analysis, we found sex specific decreases in secondary bile acids in BAC-treated mice. This finding is supported by decreases in bacteria known to metabolize primary bile acids into secondary bile acids, such as the families of Ruminococcaceae and Lachnospiraceae. We also aim to elucidate both transcriptomic (RNA sequencing) and functional (enzyme activity assays) analyses of the harvested livers from both male and female cohorts. Upstream pathway analysis from the results of these analyses is expected to yield sex specific differences in the downregulation of genes responsible for a variety of pathways such as protein digestion and absorption and transcriptional regulation in cancer. This study is expected to provide novel insights into the sex specific alterations in the relationship between the gut microbiome and liver caused by BAC exposure and the mechanisms underlying BAC toxicity.

Cell death and the processes surrounding it are essential parts of life. Ferroptosis is a distinct type of regulated cell death characterized by increased lipid peroxidation leading to cell membrane damage. The exact mechanism of ferroptotic death is currently unknown, so research is underway to discover pathways that can modulate ferroptosis. The goal of this project is to determine how different isoforms of the ACSL gene impact ferroptosis mediated by non-conjugated and conjugated polyunsaturated fatty acids (PUFAs). ACSL4 (long-chain acyl-CoA synthetase 4) is a gene of importance in ferroptosis because it incorporates PUFAs into the cell membrane. The membrane-incorporated PUFAs can be oxidized via lipid peroxidation in the cell, leading to membrane damage and eventual cell death. It has been found that knocking out or silencing the ACSL4 gene can make cells resistant to ferroptosis. I compare how ACSL4-knockout cells react to different PUFAs, and how these PUFAs sensitize wild-type and ACSL4-knockout cells differently when treated with ferroptosis-inducing drugs. Cell viability assays are a way to measure the amount of cell death in response to a treatment. I perform these assays to create dose-response curves for different lipid and drug treatments and use flow cytometry to quantify the amount of lipid peroxidation. These assays help establish a baseline comparing the response of wild-type and ACSL4-knockout cells to different PUFAs and ferroptotic drugs. Preliminary results demonstrate greater percent viability in two different knockout cell lines compared to wild-type cells when treated with the drug RSL3 and arachidonic acid. ACSL4-knockout cells are expected to have decreased cell death if they are protected from ferroptosis. Results will demonstrate the extent to which knocking out the ACSL4 gene affects cell survival. Ultimately, ferroptosis is a process of interest due to its therapeutic potential in treating tissue damage and as a targeted cancer therapy.

Hypoxic-ischemic encephalopathy (HIE), resulting from a lack of blood and oxygen flow to the brain, is the leading cause of morbidity and mortality in newborns, and currently has no cure. Our lab is investigating curcumin for use as a neuroprotectant agent, as it has anti-inflammatory, antioxidant, and antiapoptotic effects. Our current studies have been focused on further improving the drug encapsulation of curcumin in a polymeric nanoparticle platform, as well as methods to increase long-term shelf-life stability of the nanoparticle therapeutics. Previous research from our lab has successfully loaded curcumin into poly(ethylene glycol)-poly(lactic-co-glycolic acid) (PEG-PLGA) nanoparticles as a delivery vehicle. PEG-PLGA is an FDA approved, biodegradable polymer platform that allows for improved drug delivery efficiency, controlled and sustained drug release, and improved penetration and diffusion in the brain. We have shown that curcumin loaded PEG-PLGA nanoparticles have resulted in significant neuroprotection when used as a treatment for hypoxic-ischemic neonatal rats (term equivalent to human). In order to progress towards scale-up and clinical translation of the therapeutic, I have tested variations to the formulation method at every step of the formulation process, including changes in PEG-PLGA molecular weight ratios, surfactants, and organic solvents used. I have assessed the impacts of each formulation parameter on colloidal stability and drug loading, with the aim to create a scalable, stable platform that can retain drug delivery and drug activity properties during distribution and shelf-life storage. I have identified that nanoparticle drop size, surfactant type and concentration, and freezing protectant (cryoprotectant) have the biggest impact on drug loading and stability. Improving the stability is the first step in making the therapeutic more accessible, cheaper, and easier to transport for a larger impact.

Two-dimensional van der Waals materials are a class of materials that can be exfoliated into thin layers. Exotic properties can emerge in these thin-layer materials, such as electric polarization. In this presentation, we report the observation of irregular piezoelectric domains in natural flakes of thin-layer tungsten disulfide, a transition metal dichalcogenide (TMD), detected with piezoresponse force microscopy (PFM). These domains also exhibit different surface potential when analyzed with kelvin probe force microscopy, which is consistent with our PFM observation. We attribute the emergence of these intriguing domains to the formation of opposite R-stacked regions with inversion symmetry breaking, as opposed to inversion-symmetric H-stacked layers. To investigate this further, we performed reflectance measurements in a dual gated device with strong position dependent hysteresis, indicating different built-in potentials of the domains. Our work provides a new avenue to engineer electric polarization in thin-layer materials, which will contribute to applications such as information storage.