Nasseri Behrooz, Florence Alexander T
Centre for Drug Delivery Research, The School of Pharmacy, University of London, 29-39 Brunswick Square, London WC1 N 1AX, UK.
J Control Release. 2003 Oct 30;92(3):233-40. doi: 10.1016/s0168-3659(03)00298-0.
Micromanipulation of the external bilayers of nonionic surfactant vesicles (niosomes) and liposomes allows the formation of tethers, which are fluid state lipid/surfactant lamellar nanotubes. The technique allows investigation of some of the factors affecting tether formation and vesicle-tether interactions. In this paper the movement of a vesicle along, or more precisely in, tethers derived from the vesicle, has been studied. When a vesicle is supported by bipolar tethers, stretching the tether on one side of the vesicle, initiates the movement of the vesicle in the opposite direction, at velocities ranging up to 2.5 microm s(-1) thus creating a 'vesicular shuttle'. Movement of the vesicle occurs inside the tether structures, a process akin to the movement of a sphere in a flexible tube with a diameter much less than that of the sphere. The factors involved in the movement of vesicles in the tethers include the radial stretching and subsequently contraction of the tethers and the minimisation of elastic energies stored in the tether membranes. Vesicle velocity is not constant: there is deceleration near the end of the trajectory. While the relevance to the design of novel delivery systems is as yet tenuous, the system allows vesicle-vesicle collisions to be observed when the vesicle is propelled towards a stationary vesicle, and directly observation of the flow properties of vesicles in flexible 'capillaries', a neglected topic.
对非离子表面活性剂囊泡（脂质体）和脂质体的外部双层进行微操作可形成系链，系链是流体状态的脂质/表面活性剂层状纳米管。该技术能够研究一些影响系链形成和囊泡 - 系链相互作用的因素。在本文中，已经研究了囊泡沿着源自该囊泡的系链，或者更准确地说是在系链内部的运动。当一个囊泡由双极系链支撑时，拉伸囊泡一侧的系链会引发囊泡在相反方向上的运动，速度可达2.5微米每秒（-1），从而形成一个“囊泡穿梭机”。囊泡的运动发生在系链结构内部，这一过程类似于一个球体在直径远小于其自身的柔性管内的运动。囊泡在系链中运动所涉及的因素包括系链的径向拉伸以及随后的收缩，以及系链膜中储存的弹性能的最小化。囊泡速度并非恒定：在轨迹末端附近会减速。虽然与新型递送系统设计的相关性目前还很微弱，但该系统在将囊泡推向静止囊泡时能够观察到囊泡 - 囊泡碰撞，并且能够直接观察柔性“毛细管”中囊泡的流动特性，这是一个被忽视的课题。
