Design and Application of Biological Systems for Detection and Remediation of Per- and Polyfluoroalkyl Substances

Per- and polyfluoroalkyl substances (PFAS) are a large group of synthetic fluorinated chemicals with surface active and water-repellent properties that have been considered “forever chemicals” due to their rapid emergence as environmental contaminants and resistance to biological degradation. PFAS have been developed for use and production of everyday items like stains, oil and water-resistant textiles non-stick cookware and, a majority of aqueous-film forming foams used in fire suppression. The combination of wide-spread use in industrial processes and consumer products with the chemicals’ extended biological half-lives leads to accumulation of PFAS in the environment and subsequently people. Exposure and accumulation of PFAS chemicals, specifically perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), has been linked to a multitude of health effects, and a majority of human exposure is linked to ingestion through water and food grown in contaminated soils. However, remediation of these contaminants across a wide range of conditions remains difficult as their strong carbon-fluorine bonds result in limited reactivity and resistance to degradation. Even the detection of PFAS posess a unique challenge and often requires expensive and timely analysis techniques unsuitable for on-site diagnostics. As the extent of the PFAS problem continues to be revealed, the overall goal of this work is to begin addressing the need for quick, on-site detection technologies as well as feasible methods for remediation of soils using biological methods.

For detection strategies, we focused on the creation of biosensors for PFAS detection by utilizing human liver fatty acid binding protein (hLFABP) as a scaffold. Chapter 2 focuses on the development of a purified protein-based sensor capable of detecting several PFAS through a rationally incorporated fluorophore (acrylodan) while Chapter 3 shows the application of this biosensor on environmental samples and comparison to analytic methods. Chapter 4 illustrates the development of a separate biosensor based the on incorporation of circularly permuted green fluorescent protein (cpGFP) into a split hLFABP motif that is promising for genetically encoded whole cell sensing. Chapter 5 addresses remediation of soil by studying phytoaccumulation and distribution of PFAS into industrial hemp (Cannabis sativa). Collectively, this dissertation lays important groundwork for the use of synthetic biology and other biologically inspired techniques to begin overcoming the challenges in PFAS detection and remediation.