Year of Publication

2019

Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation

College

Engineering

Department

Chemical and Materials Engineering

First Advisor

Dr. Thomas D. Dziubla

Second Advisor

Dr. J. Zach Hilt

Abstract

The exposure to halogenated persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs), has been linked to numerous inflammatory diseases, including diabetes, cancer and lowered immune response. PCBs have low solubility in water, and they interact with other contaminants, making their detection quite challenging. While, there have been several attempts at improving the ease of detection and sensing of PCBs, gas chromatography-mass spectrometry (GC-MS) remains the gold standard. However, despite its ubiquitous use, GC-MS is a challenging technique that requires high skill and careful sample preparation, which are time-consuming and costly. As such, there is still a need to develop a sensing system that can detect PCBs in a more efficient manner.

In this work, we hypothesize that the dilute concentration of PCBs in water can be detected using a fluorescent displacement assay. To test this hypothesis, we screened a series of fluorescent molecules that were used as a fluorescence quenching pair. The displacement pair(BaP/curcumin) was evaluated in polymer microparticles (MPs) for higher sensitivity. Curcumin was immobilized to the MPs and BaP was kept free for easy displacement in the solution. MPs indicate good binding of BaP that does not come off in the solution. However, BaP displaces from the MPs in the presence of PCB. The enhanced signal of BaP indicates the presence of a novel hydrophobic interaction between BaP and PCB in water. This hydrophobic interaction leads to the successful detection of PCB. BaP fluorescence increases with trace concentrations of PCBs in water. To determine the selectivity and robustness of this response, the impact of pH, ionic strength and humic acid to mimic freshwater conditions are explored. BaP was able to detect PCBs in the micromolar range. The fluorescent dye was then immobilized on the polymer network for enhanced sensitivity and recovery. For this purpose, BaP analog pyrene is used, which behaves similar to BaP in water with PCB. This molecule was functionalized into the monomer and is polymerized into the hydrophilic polymer network for pH-based swelling, to allow PCBs within its network for the interaction with pyrene. These MPs are characterized using different techniques and their interaction with PCBs was studied.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2019.413

Funding Information

This work is supported by the NIEHS/NIH grant P42ES007380.

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