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Time-related formation of bioactive polycyclic aromatic hydrocarbon (PAH) photoproducts upon interaction with TiO2 nanoparticles in the aqueous phase

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StMaryL_0820_egisSS.pdf (4.815Mb)
Date
2020-08
Author
St. Mary, Lindsey
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Abstract
Polycyclic aromatic hydrocarbons (PAHs) and TiO2 nanoparticles (NPs) are environmental pollutants that possess individual photoactivity. Interactions between PAHs and TiO2-NPs can influence the environmental fate, transport, and transformation of PAHs and their photoproducts. PAH and TiO2-NP interactions are of interest due to their emerging environmental relevance, particularly with the deliberate application of TiO2-NPs to remediate pollution events (e.g., oil spills). The objective was to investigate continued PAH photoproduct formation and transformation, both in the absence and presence of TiO2-NPs, following UVA (320-400 nm) irradiation. In order to do this, multiple analytical methods were performed which included identification of PAH-specific photoproducts (e.g., oxygenated PAHs (OPAHs) and hydroxylated PAHs (OHPAHs)), assessing gene expression profiles of specific genes involved in PAH metabolism, and evaluating changes in oxidative potential. Anthracene (ANT), benzo[a]pyrene (BaP), fluoranthene (FLT), phenanthrene (PHE), and pyrene (PYR) solutions were prepared alone or in combination with TiO2-NPs in OECD medium, and UVA (7.26 mW/cm2) irradiated which were then exposed to early life stage zebrafish and collected at specific time-points following UVA irradiation. Gene expression profiles showed PAH-specific and time-dependent induction of genes in exposures of PAHs and altered bioavailability of PAHs and photoproducts in the presence of TiO2-NPs. To explore the diversity of photoproduct formation and transformation following UVA irradiation, a targeted screening of various OHPAHs and OPAHs was performed using gas chromatography-mass spectrometry (GC-MS) at the same time points assessed in zebrafish exposures. Diverse photoproducts of differing size and ring arrangements were identified, which suggested photodissociation, recombination, ring addition, and ring re-arrangements of PAHs occurred either during or following UVA irradiation. PAHs all showed heightened oxidative potential following irradiation, but TiO2-NP-related increases in oxidative potential were PAH-specific. The exploitation of biological responses and analytical chemistry to investigate changes in PAH-specific photochemistry and bioavailability upon interaction with TiO2-NPs following UVA irradiation have provided novel insights into distinct PAH photoactivity, TiO2-NP influence on photoproduct formation in a PAH-specific manner, and the significant role time plays in all of these processes.
URI
http://hdl.handle.net/10399/4435
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©Heriot-Watt University, Edinburgh, Scotland, UK EH14 4AS.

Maintained by the Library
Tel: +44 (0)131 451 3577
Library Email: libhelp@hw.ac.uk
ROS Email: open.access@hw.ac.uk

Scottish registered charity number: SC000278

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AboutCopyright
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