Department of Mathematics, Fordham University, The Bronx, New York, USA.
Biophys J. 2011 Dec 21;101(12):2929-38. doi: 10.1016/j.bpj.2011.11.009. Epub 2011 Dec 20.
A new theory, to our knowledge, is developed that describes the dynamics of a lipidic pore in a liposome. The equations of the theory capture the experimentally observed three-stage functional form of pore radius over time--stage 1, rapid pore enlargement; stage 2, slow pore shrinkage; and stage 3, rapid pore closure. They also show that lipid flow is kinetically limited by the values of both membrane and aqueous viscosity; therefore, pore evolution is affected by both viscosities. The theory predicts that for a giant liposome, tens of microns in radius, water viscosity dominates over the effects of membrane viscosity. The edge tension of a lipidic pore is calculated by using the theory to quantitatively account for pore kinetics in stage 3, rapid pore closing. This value of edge tension agrees with the value as standardly calculated from the stage of slow pore closure, stage 2. For small, submicron liposomes, membrane viscosity affects pore kinetics, but only if the viscosity of the aqueous solution is comparable to that of distilled water. A first-principle fluid-mechanics calculation of the friction due to aqueous viscosity is in excellent agreement with the friction obtained by applying the new theory to data of previously published experimental results.
据我们所知，一项新理论发展起来了，它描述了脂质体中脂孔的动力学。该理论的方程捕捉到了实验观察到的孔径随时间的三阶段功能形式——阶段 1，快速孔扩大；阶段 2，缓慢孔收缩；阶段 3，快速孔关闭。它们还表明，脂质流动受到膜和水粘度值的动力学限制；因此，孔的演化受到两种粘度的影响。该理论预测，对于半径数十微米的巨大脂质体，水粘度将主导膜粘度的影响。利用该理论计算脂质孔的边缘张力，定量解释了阶段 3 中快速孔关闭的孔动力学。该边缘张力值与从缓慢孔关闭阶段 2 标准计算的值一致。对于较小的亚微米脂质体，膜粘度会影响孔动力学，但前提是水溶液的粘度与蒸馏水相当。水粘度引起的摩擦的第一性原理流体力学计算与通过将新理论应用于先前发表的实验结果的数据获得的摩擦非常吻合。
