Nasseri Behrooz, Florence Alexander T
Centre for Drug Delivery Research, The School of Pharmacy, University of London, 29-39 Brunswick Square, London WC1N 1AX, UK.
Int J Pharm. 2003 Mar 18;254(1):11-6. doi: 10.1016/s0378-5173(02)00669-5.
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.
多面体非离子表面活性剂囊泡（脂质体）在机械应力作用下会发生复杂的形状转变。当在压力下从出口直径小于囊泡直径的毛细管中挤出时，可形成一系列主要由小管、管内囊泡和同心结构组成的新颖结构。微管（长度可达80微米）是由于对多面体脂质体施加压力而形成的，这导致许多囊泡融合，相对剪切力使囊泡移动，从而形成三种独特的结构，即小管、管内囊泡和同心（“涡旋”）形态。已使用模型溶质5(6)-羧基荧光素（CF）研究了小管的包封效率，以及剪切应力和压实压力对包封溶质释放的影响。结构的变形会影响其保留包封溶质的能力。加热到转变温度以上的管状结构会可逆地转变为离散的囊泡结构。
