title: Size distribution measurement of vesicles by atomic force microscopy.
abstract: Vesicles have been utilized as nanoscale vehicles for reagents including potential drug delivery systems. When used to deliver drugs, vesicle size and the size distribution are important factors in the determination of the dosage, cell specificity, and rate of clearance from the body. Current size measurement techniques for vesicles are electron microscopy and dynamic light scattering, but their results are not equal. Therefore atomic force microscopy was attempted as another size measurement technique. After adsorption of the vesicles from a low-concentration solution of vesicles on mica substrate, each vesicle is generally found as a flattened structure. The diameters of vesicles in these solutions and their distribution have been successfully estimated from the surface area of the flattened structure of each vesicle. At higher concentrations, we have found a monolayer crammed with dome-shaped vesicles on the substrate. The diameters of vesicles in these solutions have also been successfully estimated from the surface area of the dome-shaped structure of each vesicle. Diameters of vesicles in solution estimated from two different vesicle concentrations are not close to those reported by electron microscope studies but are close to those reported by dynamic light scattering studies.
authors.affiliation: Department of Atomic Scale Science, Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka, Ibaraki, Osaka 567-0047, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kanno
authors.forename: Tadanori
authors.initials: T
authors.lastname: Yamada
authors.forename: Hidehiko
authors.initials: H
authors.lastname: Iwabuki
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Tanaka
authors.forename: Shun'ichi
authors.initials: S
authors.lastname: Kuroda
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Tanizawa
authors.forename: Tomoji
authors.initials: T
authors.lastname: Kawai
mesh_terms: D000327:Adsorption; D000538:Aluminum Silicates / Q000737:chemistry; D006514:Hepatitis B Surface Antigens / Q000032:analysis* / Q000096:biosynthesis / Q000737:chemistry; D008081:Liposomes / Q000032:analysis* / Q000737:chemistry; D018625:Microscopy, Atomic Force / Q000379:methods*; D010316:Particle Size; D010957:Plasmids; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D016008:Statistical Distributions; D013499:Surface Properties
chemical_list: D000538:Aluminum Silicates; D006514:Hepatitis B Surface Antigens; D008081:Liposomes; C011934:mica