Some properties of extruded non-ionic surfactant micro-tubes.
Polyhedral non-ionic surfactant vesicles (niosomes) undergo complex shape transitions as a result of mechanical stress. When extruded under pressure from capillaries with exit diameters smaller than the diameter of the vesicles, a series of novel structures comprising mostly of tubules, vesicles inside tubules and concentric structures can be formed. The microtubules (up to 80 microm in length) form as a result of the pressure exerted on polyhedral niosomes, this leading to the fusion of many vesicles, the relative shear giving movement of the vesicles giving rise to the formation of three distinctive structures, namely tubules, vesicle within tubule and concentric ("whorl") morphologies. The entrapment efficiency of the tubules has been studied using a model solute 5(6)-carboxyfluorescein (CF), as has the effect of shear stress this and compaction pressure on the release of the entrapped solute. Deformation of the structures affects their ability to retain entrapped solute. Tubular structures heated above their transition temperatures reversibly transform into discrete vesicular structures.
Nasseri
Behrooz
B
Centre for Drug Delivery Research, The School of Pharmacy, University of London, 29-39 Brunswick Square, London WC1N 1AX, UK.
Florence
Alexander T
AT
D002626:Chemistry, Pharmaceutical; D016503:Drug Delivery Systems; D005452:Fluoresceins / Q000032:analysis / Q000737:chemistry; D008863:Microspheres; D010316:Particle Size; D011092:Polyethylene Glycols / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry*; D013997:Time Factors; D014743:Videotape Recording
D005452:Fluoresceins; D013501:Surface-Active Agents; C024098:6-carboxyfluorescein; D011092:Polyethylene Glycols