Date of Degree
MS (Master of Science)
First Committee Member
Second Committee Member
Hans J Lehmler
Third Committee Member
Garry R Buettner
Polychlorinated biphenyls (PCBs) are persistent environmental chemicals. Mono-hydroxylated polychlorinated biphenyls (OH-PCBs) are PCB metabolites found commonly in human blood, environmental water and sediment samples. Detection of small amounts of PCBs and their OH-PCB metabolites in biological matrices from epidemiological and laboratory studies remains a challenge.
The application of aptamers is studied as a means to identify and quantify PCBs and OH-PCBs. Aptamers are single stranded short oligonucleotides that arrange into unique shape of three-dimensional structures when binding to their target. Like antibodies they have high affinity and specificity for their specific target. The hypothesis is that aptamers can identify PCBs and PCB metabolites in environmental and biological samples. To test this hypothesis, three different OH-PCBs, 4’-OH-PCB3, 4-OH-PCB72 and 2-OH-PCB106 along with 4-OH-biphenyl as a control, were covalently attached to beads with carboxylic acid groups on their surface. Several methods were explored to characterize covalent binding of OH-PCBs to the beads: FTIR-spectroscopy, Dynamic Light Scattering (DLS) and Zeta-Potential (ZP) measurements. The beads were then used in in vitro assays to test binding of two different aptamers specific to OH-PCBs. In this study, these aptamers were tested for the ability to distinguish structurally different OH-PCB congeners and other environmental pollutants.
In future studies, aptamers can be selected for a PCB metabolite of interest, 4’-OH-PCB3, via a modified form of Systemic Evolution of Ligands by Exponential Enrichment (SELEX). Single stranded DNA (ssDNA) aptamers generated will be applied as a biosensor for the detection and quantification of traces of 4’-OH-PCB3.
Polychlorinated biphenyls (PCBs) are small chemicals present in low quantities in the environment: in food, water, air, sediments, and both human and animal tissues. Studies have shown PCBs are toxic and associated with diseases that affect the overall normal function of human organs. PCBs also cause cancer and were officially classified in 2013 as human carcinogens by The International Agency for Research on Cancer (IARC). It is therefore important to have methods to detect these toxic compounds.
The present study involves the detection of PCBs and its intermediates, which are the PCB metabolites, when inside the human body. Hydroxylated polychlorinated biphenyls (OH-PCBs) are PCB metabolites found commonly in human blood, environmental water and sediment samples. The detection of PCBs and OH-PCBs, a necessity for human health protection, remains challenging and expensive. As a novel approach to solve this problem, aptamers for the detection of PCBs and PCB metabolites is proposed. Aptamers are applied as biosensors for the detection and quantification of traces of these molecules. Aptamers are essentially the building blocks of what constitutes genetic information such as DNA that are capable of binding to their target very specifically, like a key and lock model. The hypothesis is the application of these DNA aptamers can be used as a means to identify PCBs and OH-PCBs.
This work is important because it will aid in the development of novel methods for the identification of PCBs in biological and environmental samples and the unveiling of adverse health effects of PCBs in humans.
Aptamers, Biosensors, Metabolites of PCBs, Methods of detection, OH-PCBs
ix, 77 pages
Includes bibliographical references (pages 71-77).
Copyright © 2016 Marisa Genevive Salomon Beltran
Salomon Beltran, Marisa Genevive. "Novel tools for targeting PCBs and PCB metabolites using ssDNA aptamers." MS (Master of Science) thesis, University of Iowa, 2016.