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Nanomolar PFOA Concentrations Affect Lipid Membrane Structure: Consequences for Bioconcentration Mechanisms
Tess N Sobolewski1, Rhys C Trousdale1, Colin L Gauvin1
1Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United States.
Environmental Science & Technology
|December 24, 2024
Summary
Perfluorooctanoic acid (PFOA), a PFAS chemical, alters DPPC vesicle bilayers at low concentrations. This changes bilayer properties, increasing susceptibility to solute accumulation and causing membrane hydration.
Area of Science:
- Environmental Science
- Biochemistry
- Materials Science
Background:
- PFAS chemicals, like PFOA, are persistent environmental contaminants.
- Lipid bilayers, such as DPPC vesicles, are fundamental to cell membranes and drug delivery systems.
- Understanding how environmental contaminants interact with biological membranes is crucial.
Purpose of the Study:
- To investigate the effects of perfluorooctanoic acid (PFOA) on dipalmitoylphosphatidylcholine (DPPC) vesicle bilayers.
- To elucidate the structural and functional changes induced by PFOA in lipid bilayers.
- To assess the impact of PFOA on bilayer permeability and solute interactions.
Main Methods:
- Calorimetry measurements to determine changes in DPPC's gel-liquid crystalline transition enthalpy.
- Dynamic light scattering (DLS) to analyze vesicle size distribution and identify smaller structures.
- Cryo-electron microscopy (cryo-EM) for detailed structural analysis of vesicles.
- Time-resolved fluorescence emission measurements using Coumarin 152 (C152) to probe bilayer partitioning and hydration.
Main Results:
- Sub-micromolar PFOA concentrations lowered DPPC's transition enthalpy without altering the transition temperature.
- DLS data showed a broadening of DPPC vesicle size distribution and the formation of smaller (30-50 nm) bilayer structures.
- Cryo-EM revealed PFOA-induced multilamellar vesicles and bilayer structures similar to niosomes.
- PFOA increased solute (C152) partitioning into the hydrophobic interior and induced membrane hydration below the transition temperature.
Conclusions:
- PFOA significantly alters DPPC vesicle bilayer structure and properties even at very low concentrations.
- These structural changes enhance the susceptibility of DPPC bilayers to secondary solute accumulation.
- PFOA induces membrane hydration, impacting bilayer function below the gel-liquid crystalline transition temperature.
