Karlsruhe Institute of Technology (KIT), Institute of Mechanical Process Engineering and Mechanics, Straße am Forum 8, 76131 Karlsruhe, Germany.
Soft Matter. 2018 May 16;14(19):3730-3737. doi: 10.1039/c8sm00005k.
Adsorption of phosphatidylcholines at oil/water interfaces strongly deviates from spread monolayers at air/water surfaces. Understanding its nature and consequences could vastly improve applications in medical nanoemulsions and biotechnologies. Adsorption kinetics at interfaces of water with different oil phases were measured by profile analysis tensiometry. Adsorption kinetics for 2 different phospholipids, DPPC and POPC, as well as 2 organic phases, squalene and squalane, show that formation of interfacial monolayers is initially dominated by stress-relaxation in the first minutes. Diffusion only gradually contributes to a decrease in interfacial tension at later stages of time and higher film pressures. The results can be applied for the optimization of emulsification protocols using mechanical treatments. Emulsions using phospholipids with unsaturated fatty acids are dominated much more strongly by stress-relaxation and cover interfaces very fast compared to those with saturated fatty acids. In contrast, phospholipid layers consisting of saturated fatty acids converge faster towards the equilibrium than those with unsaturated fatty acids.
磷脂在油水界面的吸附强烈偏离空气/水表面的展开单层。了解其性质和后果可以极大地提高在医学纳米乳液和生物技术中的应用。通过轮廓分析张力法测量了不同油相水界面的吸附动力学。对于 2 种不同的磷脂，DPPC 和 POPC，以及 2 种有机相，角鲨烯和角鲨烷，吸附动力学表明，在最初的几分钟内，界面单层的形成最初主要由应力松弛控制。在稍后的时间和更高的膜压阶段，扩散才逐渐有助于降低界面张力。这些结果可用于通过机械处理优化乳化方案。与含有饱和脂肪酸的磷脂相比，含有不饱和脂肪酸的磷脂形成的乳液受应力松弛的影响更大，并且与饱和脂肪酸相比，其覆盖界面的速度更快。相比之下，由饱和脂肪酸组成的磷脂层比含有不饱和脂肪酸的磷脂层更快地收敛到平衡。
