Kinetics of liposome adhesion on a mercury electrode
Kinetics of liposome adhesion on a mercury electrode
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DOI：
10.1021/jp050816s
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发表时间：
2005-08-04
影响因子：
3.3
通讯作者：
Thede, R
中科院分区：
文献类型：
--
作者：
Hellberg, D;Scholz, F;Thede, R
脂质体在汞电极上的粘附由于卵磷脂单层岛的形成而导致电容信号。电流-时间瞬变的积分给出了可以通过经验方程Q（t）= Q（0）+ Q（1）拟合的充电-时间瞬变。（1 - exp（-t/tau（1）+ Q（2）（1 - exp（-t/tau（2），其中右侧的第一项由脂质体在汞表面上的对接引起，第二项由脂质体的打开引起，第三项是由卵磷脂岛在汞表面上的扩展引起的。两个时间常数τ（1）和τ（2）的温度依赖性和总粘附速率的温度依赖性允许确定凝胶相1，2-二肉豆蔻酰-sn-甘油-3-磷酸胆碱（DMPC）和液晶相DMPC脂质体的打开、铺展和总粘附过程的活化能。在所有情况下，扩散都是速率决定过程。液晶相DMPC脂质体的铺展和整体粘附过程的负表观活化能可以通过考虑完整脂质体和打开但尚未铺展的脂质体的弱吸附平衡来解释。反应方案的正式动力学分析支持用于拟合充电时间瞬变的经验方程。所开发的脂质体粘附在汞上的动力学模型类似于先前发表的描述脂质体融合的动力学模型。新方法可用于探测脂质体膜的稳定性。
The adhesion of liposomes on a mercury electrode leads to capacitive signals due to the formation of islands of lecithin monolayers. Integration of the current-time transients gives charge-time transients that can be fitted by the empirical equation Q(t) = Q(0) + Q(1)(1 - exp(-t/tau(1))) + Q(2)(1 - exp(-t/tau(2))), where the first term on the right side is caused by the docking of the liposome on the mercury surface, the second term is caused by the opening of the liposome, and the third term is caused by the spreading of the lecithin island on the mercury surface. The temperature dependence of the two time constants tau(1) and tau(2) and the temperature dependence of the overall adhesion rate allow determination of the activation energies of the opening, the spreading, and the overall adhesion process both for gel-phase 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and for liquid-crystalline-phase DMPC liposomes. In all cases, the spreading is the rate-determining process. Negative apparent activation energies for the spreading and overall adhesion process of liquid-crystalline-phase DMPC liposomes can be explained by taking into account the weak adsorption equilibria of the intact liposomes and the opened but not yet spread liposomes. A formal kinetic analysis of the reaction scheme supports the empirical equation used for fitting the charge-time transients. The developed kinetic model of liposome adhesion on mercury is similar to kinetic models published earlier to describe the fusion of liposomes. The new approach can be used to probe the stability of liposome membranes.