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Surface Rheological Properties and Microstructures of DPPC/POPC Monolayers.
Wisnu Arfian Anditya Sudjarwo1, Jose Luis Toca-Herrera1
1Institut für Biophysik, Universität für Bodenkultur Wien (BOKU), Vienna 1190, Austria.
Langmuir : the ACS Journal of Surfaces and Colloids
|June 20, 2025
Summary
Lipid monolayer behavior was studied using surface pressure-area (π-A) isotherms and atomic force microscopy (AFM). Mixtures with POPC increased hysteresis, indicating altered molecular packing and monolayer dynamics.
Area of Science:
- Physical Chemistry
- Materials Science
- Biophysics
Background:
- Lipid monolayers exhibit complex phase behaviors influenced by molecular composition and environmental conditions.
- Understanding lipid monolayer mechanics is crucial for applications in drug delivery, biomaterials, and nanotechnology.
Purpose of the Study:
- To investigate the impact of lipid mixture composition on monolayer properties.
- To elucidate the relationship between molecular packing, phase transitions, and mechanical response.
- To characterize the viscoelastic behavior of lipid monolayers under varying conditions.
Main Methods:
- Analysis of surface pressure-area (π-A) isotherm curves and hysteresis.
- Atomic Force Microscopy (AFM) for microstructure imaging and domain visualization.
- Interfacial dilatational rheology via barrier oscillation and Lissajous plots.
Main Results:
- DPPC monolayers showed minimal hysteresis, indicating high mechanical reversibility.
- Incorporation of POPC increased hysteresis, disrupting tight packing and altering monolayer dynamics.
- AFM revealed lipid domains corresponding to LE-LC phase transitions and LC phases.
- Rheological studies quantified the influence of lipid mixture, surface pressure, frequency, and amplitude on elastic and viscoelastic properties.
Conclusions:
- Lipid monolayer behavior is highly sensitive to composition and applied surface pressure.
- Hysteresis analysis and AFM imaging provide complementary insights into lipid packing and phase transitions.
- Interfacial dilatational rheology offers a quantitative approach to characterizing monolayer mechanical responses, distinguishing linear and nonlinear regimes.
