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Some properties of extruded non-ionic surfactant micro-tubes
Behrooz Nasseri1, Alexander T Florence
1Centre for Drug Delivery Research, The School of Pharmacy, University of London, 29-39 Brunswick Square, London WC1N 1AX, UK.
International Journal of Pharmaceutics
|March 5, 2003
Summary
Mechanical stress transforms polyhedral non-ionic surfactant vesicles (niosomes) into novel tubular and concentric structures. These structures exhibit altered solute entrapment and release properties, with temperature-dependent reversibility.
Area of Science:
- Colloid and Surface Science
- Materials Science
- Biophysical Chemistry
Background:
- Polyhedral non-ionic surfactant vesicles, known as niosomes, are susceptible to mechanical stress.
- Understanding niosome deformation is crucial for drug delivery and materials science applications.
Purpose of the Study:
- To investigate the shape transitions of polyhedral niosomes under mechanical stress.
- To characterize the novel structures formed and their solute entrapment/release properties.
Main Methods:
- Extrusion of niosomes through capillaries with controlled diameters.
- Microscopy to observe structural changes.
- Entrapment efficiency studies using 5(6)-carboxyfluorescein (CF).
- Assessment of shear stress and compaction pressure effects on solute release.
Main Results:
- Polyhedral niosomes form tubules, vesicles within tubules, and concentric ('whorl') structures upon extrusion.
- Tubular structures exhibit varying entrapment efficiencies for CF.
- Shear stress and compaction pressure influence the release rate of entrapped solutes.
- Thermal treatment above transition temperatures causes reversible transformation of tubules to vesicles.
Conclusions:
- Mechanical stress induces complex, predictable shape transitions in polyhedral niosomes.
- The resulting structures have implications for controlled solute delivery.
- Niosome morphology and stability are sensitive to mechanical and thermal conditions.