title: Statistical fluctuation in zeta potential distribution of nanoliposomes measured by on-chip microcapillary electrophoresis.
abstract: 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.
authors: Department of Bioengineering, School of Engineering, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan.
authors: Kei
authors: K
authors: Kato
authors: Masaru
authors: M
authors: Koido
authors: Masashi
authors: M
authors: Kobayashi
authors: Takanori
authors: T
authors: Akagi
authors: Takanori
authors: T
authors: Ichiki
mesh_terms: D046209:Electrophoresis, Microchip / Q000379:methods*; D005452:Fluoresceins / Q000737:chemistry; D005456:Fluorescent Dyes / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D010718:Phosphatidylserines / Q000737:chemistry; D010767:Phosphorylcholine / Q000737:chemistry; D016062:Porosity; D015203:Reproducibility of Results
chemical_list: D005452:Fluoresceins; D005456:Fluorescent Dyes; D008081:Liposomes; D010718:Phosphatidylserines; D010767:Phosphorylcholine; C007740:fluorexon