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Polyelectrolyte-induced peeling of charged multilamellar vesicles
Edith Vivares1, Laurence Ramos
1Laboratoire des Colloïdes, Verres et Nanomatériaux (UMR CNRS-UM2 5587), CC26, Université Montpellier 2, 34095 Montpellier Cedex 5, France.
Langmuir : the ACS Journal of Surfaces and Colloids
|March 9, 2005
Summary
Charged polyelectrolytes (PEs) and surfactants form aggregates. The isoelectric point dictates aggregate structure, with PEs inducing bilayer peeling in multilamellar vesicles (MLVs).
Area of Science:
- Colloid and Surface Science
- Materials Science
- Biophysics
Background:
- Charged surfactants form vesicles in solution.
- Polyelectrolytes (PEs) are polymers with charged groups.
- Mixtures of surfactants and PEs can exhibit complex phase behavior.
Purpose of the Study:
- Investigate the phase behavior of charged surfactant and oppositely charged polyelectrolyte mixtures.
- Determine the role of the polyelectrolyte-to-surfactant charge ratio (x) on aggregate formation.
- Understand the dynamics of polyelectrolyte/surfactant complex formation and multilamellar vesicle (MLV) disruption.
Main Methods:
- Light microscopy to observe aggregate formation and vesicle dynamics in real time.
- X-ray scattering to analyze the microscopic structure of aggregates.
- Systematic variation of the polyelectrolyte-to-surfactant charge ratio (x).
Main Results:
- For x > 0, aggregates are formed.
- The isoelectric point significantly influences aggregate morphology and structure (differences observed for x ≤ 1 vs. x > 1).
- Polyelectrolytes induce a "peeling" of multilamellar vesicle bilayers, leading to vesicle disruption and aggregate formation.
Conclusions:
- The isoelectric point is critical for dictating the structure of polyelectrolyte/surfactant aggregates.
- A novel phenomenon of sequential bilayer peeling is observed in MLVs upon PE addition.
- This peeling is attributed to PE-induced tension and pore formation/growth in surfactant bilayers.