UB researchers to study how replacement ‘forever chemicals’ build up in fish

BUFFALO, N.Y. — Fluorotelomers were introduced as safer versions of per- and polyfluoroalkyl substances (PFAS), but recent studies suggest they may build up in fish much like the “forever chemicals” they replaced. 

Understanding the risks these replacement PFAS pose to aquatic life requires a clearer picture of how they accumulate in fish at the molecular level.

Now, scientists from the University at Buffalo’s RENEW Institute will examine how fluorotelomers latch onto fish cell membranes and interact with key protein gatekeepers, thanks to a one-year, $250,000 Strategic Environmental Research and Development Program (SERDP) grant from the U.S. Department of Defense.

RENEW chemists Diana Aga, G. Ekin Atilla-Gokcumen and Alexander Hoepkner are co-investigators on the project and will lead the experimental work. The computational component will be led by principal investigator Angela Wilson, PhD, John A. Hannah Distinguished Professor of Chemistry at Michigan State University.

“By understanding the rules that dictate how these newer forms of forever chemicals settle into different parts of a fish, we are developing better ways to measure environmental risk and protect our aquatic ecosystems,” says Aga, PhD, director of RENEW and SUNY Distinguished Professor and Henry M. Woodburn Chair in the UB Department of Chemistry.

Fluorotelomers were thought to be less persistent than legacy PFAS like perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) because they have shorter chains of carbon. However, they appear to be bioaccumulating in plants and animals all the same.  

They’re often used in aqueous film-forming foam, a firefighting agent long used at military bases, airports and industrial sites that can soak into soil and eventually flow into waterways. 

The RENEW team will examine how fluorotelomers, as well as other types of PFAS found in this firefighting foam, enter the cells of zebrafish, a freshwater species widely used in research because many of its biological processes are similar to those in humans.

“If replacement PFAS accumulate in fish the same way legacy PFAS do, that has important implications for environmental risk,” Aga says.

One way PFAS penetrate cells is by interacting with the lipids that form the cell membrane. They may also interact with transporter proteins embedded within the membrane that regulate what enters and leaves the cell.

“The cell membrane represents the first protective barrier of a cell and plays a critical role in its biological functions,” says Atilla-Gokcumen, PhD, Dr. Marjorie E. Winkler Distinguished Professor and associate chair of the UB Department of Chemistry. “To understand how PFAS accumulate in cells, we need to know the molecular mechanisms that control interactions at the cell membrane.” 

Atilla-Gokcumen will lead the in vitro experiments to identify genes and proteins that facilitate the uptake of different PFAS through exposure studies in cell line models of zebrafish.

A unique aspect of this study is the use of fluorine-19 nuclear magnetic resonance (¹⁹F NMR) spectroscopy to determine how different parts of the molecule interact with the cell membrane. 

“Because PFAS molecules contain many fluorine atoms, this technique can tell us how readily PFAS embed themselves into the fatty cell membrane versus staying dissolved in water,” says Hoepker, PhD, a RENEW senior research scientist who will perform the experiments. 

Aga will also use another advanced technique available at the RENEW Institute, ion mobility mass spectrometry, to determine how differences in PFAS shape and size affect their interactions with membrane proteins. 

This will build upon Aga’s previous research that found supermarket fish tend to accumulate more branched isomers than linear isomers of PFOS. Branched isomers are more compact and dissolve more easily in water, while linear isomers are elongated and tend to bind more strongly to proteins.

The computational component, led by Wilson’s team at Michigan State, will use AlphaFold — an artificial intelligence program that predicts protein structures to model the transporter proteins. Further, molecular dynamics simulations will be used to reveal how PFAS interact with lipid membranes and bind to transporter proteins over time.

This is the second SERDP grant awarded to a team of RENEW scientists. Hoepker, along with Steven Ray, PhD, associate professor of chemistry, and RENEW Senior Research Scientist Joshua Wallace, PhD, are currently pursuing a separate SERDP-funded project to thermally remove PFAS from granular activated carbon (GAC) filters and then destroy the vaporized PFAS using specialized microwave plasma technology. The technique could make GAC filters, used in both home water pitchers and municipal treatment plants, reusable.