Department of Bioengineering, School of Engineering, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan.
Electrophoresis. 2013 Apr;34(8):1212-8. doi: 10.1002/elps.201200549. Epub 2013 Mar 18.
The zeta potential of nanoliposomes with a diameter below 100 nm has been studied by the combined use of on-chip microcapillary electrophoresis (μCE) and sensitive fluorescence imaging. Tracking the electrophoretic migration of individual nanoliposomes has enabled the accurate evaluation of the zeta potential distribution of nanoliposomes and the first observation of its abnormal broadening due to a statistical fluctuation phenomenon specific to the "nanoscale world." The materials used for liposome preparation were phosphocholine as the neutral lipid, phosphatidylserine as the anionic lipid, and cholesterol. The size of the liposomes encapsulating calcein, a fluorescent dye used for imaging convenience, was tailored by extrusion through polycarbonate membrane filters of different pore sizes ranging from 50 to 1000 nm. The on-chip μCE system comprised a μCE chip, a laser source, an inverted microscope, and an electron-multiplying charge-coupled device camera. The electrophoresis experiment using this system revealed that the relative standard deviation of the zeta potential distribution of nanoliposomes is inversely proportional to their diameter and apparently increases below 100 nm. This abnormal broadening of zeta potential distribution of nanoliposomes is explained by prominent discreteness effect of the number of anionic lipid molecules in nanoliposomes.
通过结合使用片上微毛细管电泳 (μCE) 和灵敏的荧光成像技术，研究了直径小于 100nm 的纳米脂质体的 ζ 电位。通过跟踪单个纳米脂质体的电泳迁移，可以准确评估纳米脂质体的 ζ 电位分布，并首次观察到由于“纳米世界”特有的统计波动现象导致 ζ 电位分布异常变宽。用于脂质体制备的材料是磷酸胆碱作为中性脂质，磷脂酰丝氨酸作为阴离子脂质，胆固醇。通过在聚碳酸酯膜过滤器中挤压，将包封荧光染料钙黄绿素的脂质体的大小调整为 50 至 1000nm 不同孔径。片上 μCE 系统包括 μCE 芯片、激光源、倒置显微镜和电子倍增电荷耦合器件相机。使用该系统进行的电泳实验表明，纳米脂质体的 ζ 电位分布的相对标准偏差与它们的直径成反比，并且在 100nm 以下明显增加。纳米脂质体 ζ 电位分布的这种异常变宽可以通过纳米脂质体中阴离子脂质分子数量的显著离散效应来解释。
