PFAS fluidize synthetic and bacterial lipid monolayers based on hydrophobicity and lipid charge

Aleksandra Naumann,Jessica Alesio,Monika Poonia,Geoffrey D Bothun

doi:10.1016/j.jece.2022.107351

Aleksandra Naumann, Jessica Alesio + Show 2 more

Open Access

https://doi.org/10.1016/j.jece.2022.107351

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Abstract

Poly- and Perfluoroalkyl substances (PFASs) are pollutants of emerging concern that persist in nature and pose environmental health and safety risks. PFAS disrupt biological membranes resulting in cellular inhibition, but the mechanism of disruption and the role of lipid composition remain unclear. We examine the role of phospholipid saturation and headgroup charge on the interactions between PFASs and phospholipid monolayers comprised of synthetic phosphocholine (PC) and phosphoglycerol (PG) lipids and prepared from bacteria membrane extracts rich in PG lipids from an environmentally relevant marine bacterium Alcanivorax borkumensis. When deposited on a buffered subphase containing PFAS, PFAS mixed within and fluidized zwitterionic and net-anionic monolayers leading to increases in monolayer compressibility that were driven by a combination of PFAS hydrophobicity and monolayer charge density. Differences in the monolayer response using saturated or unsaturated lipids are attributed to the ability of the unsaturated lipids to accommodate PFAS within ‘void space’ arising from the bent lipid tails. Similar fluidization and compressibility behavior were also observed in A. borkumensis lipid monolayers. This work provides new insight into PFAS partitioning into bacterial membranes and the effect PFAS have on the physicomechanical properties of zwitterionic and charged lipid monolayers.

Highlights

Poly- and Perfluoroalkyl substances (PFAS) are pollutants of emerging concern that exhibit an unprecedented ability to accumulate within the environment.[1–3] PFAS, which are fluorinated amphiphiles with low volatility, have been used in a wide range of products and processes where low adhesion and water and oil repellency are required.[4,5] These properties cause PFAS to persist in the environment and bioaccumulate
PFAS are soluble in water and upon compression the results reflect a competition between PFAS packing at the air/water interface and the adsorption energy
Perfluorooctanoic acid (PFOA) exhibited an s-shaped curve with π increasing from 4.2 to 11.5 mN/m with compression as PFOA packed more tightly at the interface and reduced the interfacial tension

Summary

Introduction

Poly- and Perfluoroalkyl substances (PFAS) are pollutants of emerging concern that exhibit an unprecedented ability to accumulate within the environment.[1–3] PFAS, which are fluorinated amphiphiles with low volatility, have been used in a wide range of products and processes where low adhesion and water and oil repellency are required.[4,5] These properties cause PFAS to persist in the environment and bioaccumulate. PFAS, which are fluorinated amphiphiles with low volatility, have been used in a wide range of products and processes where low adhesion and water and oil repellency are required.[4,5]. These properties cause PFAS to persist in the environment and bioaccumulate. One of the moststudied PFAS, perfluorooctanesulfonic acid (PFOS) is known to be present in blood serum of US citizens at concentrations near 40 ng/mL.[6]. The short-chain PFAS perfluorobutanesulfonic acid (PFBS) found in cord blood was positively associated with preeclampsia.[7]. High levels of PFAS remain in the body.[8,9] there has been a shift to PFAS with shorter fluorinated tails that are thought to bioaccumulate to a lesser extent than longer PFAS, compounds with long fluorinated tails (CnF ≥ 7) remain in the environment, even in remote areas such as the arctic through the global water cycle.[6,10,11]

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