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Nanoscale properties of mixed fengycin/ceramide monolayers explored using atomic force microscopy
1Unité de Chimie Biologique Industrielle and Unité de Bio-industries, Faculté Universitaire des Sciences Agronomiques de Gembloux, Passage des Déportés, 2, B-5030 Gembloux, Belgium.
Langmuir : the ACS Journal of Surfaces and Colloids
|March 9, 2005
Summary
Fengycin interacts with skin lipids, forming distinct molecular arrangements. Environmental factors and fengycin concentration significantly alter these structures, suggesting a biological role in modulating skin membrane organization.
Area of Science:
- Biophysics
- Materials Science
- Dermatology
Background:
- Skin membrane lipids, like ceramides, are crucial for barrier function.
- Fengycin, a cyclic lipopeptide, has potential pharmaceutical applications.
- Understanding fengycin-ceramide interactions is key to exploring its biological effects on skin.
Purpose of the Study:
- To investigate the molecular interactions between fengycin and ceramide in mixed monolayers.
- To determine how environmental conditions (temperature, pH) and fengycin concentration affect these interactions.
- To elucidate the potential biological implications of fengycin's effect on skin membrane organization.
Main Methods:
- Atomic Force Microscopy (AFM) to visualize monolayer topography, friction, and adhesion.
- Surface pressure-area isotherms to analyze monolayer properties at the air-water interface.
- Thermodynamic analysis (deviation from additivity rule, excess free energy) to quantify interactions.
Main Results:
- Mixed fengycin/ceramide monolayers exhibit phase separation with distinct ceramide crystalline domains and fengycin-enriched fluid phases at lower temperatures and pH.
- Ceramide forms ordered domains, while fengycin adopts a disordered, horizontal orientation.
- Elevated temperature and pH (mimicking skin conditions) disrupt domain structures, leading to rounded domains or a continuous fluid phase depending on fengycin concentration.
Conclusions:
- Fengycin and ceramide interactions are highly sensitive to temperature, pH, and fengycin concentration.
- These environmental factors and fengycin concentration significantly influence the molecular organization and domain formation in mixed monolayers.
- Fengycin's ability to modulate skin membrane lipid organization may represent a significant biological function warranting further pharmacological investigation.