title: Preparation and characterization of a new lipid nano-emulsion containing two cosurfactants, sodium palmitate for droplet size reduction and sucrose palmitate for stability enhancement.
abstract: A new lipid nano-emulsion (LNE) was prepared from soybean oil and phosphatidylcholine (PC) employing two cosurfactants, sodium palmitate (PA) for reduced droplet size and sucrose palmitate (SP) for stability enhancement. The mean droplet size of LNEs prepared at a PA/PC (w/w) ratio of larger than 1/10 was found to be ca. 50 nm by dynamic light scattering and atomic force microscopy. However, during the 12-month storage, the PA/PC (1/10)-LNE showed an increase in mean droplet size and broadening of the droplet size distribution due to coalescence of the LNE particles. In a saline solution, the coalescence proceeded very rapidly, i.e., the mean droplet size increased to more than 150 nm within 0.5 h. To suppress the coalescence of LNE particles, four sucrose fatty acid esters of different chain lengths were examined as candidate cosurfactants. The results showed that PA/SP/PC (1/4/10)-LNE could maintain a mean droplet size around 50 nm for 12 months. In a saline solution, the mean droplet size could be maintained within 100 nm even after 24 h. Slight formation of flocculation in the LNEs depending on the storage period was suggested by measurement of the 31P nuclear magnetic resonance line width of the LNEs.
authors.affiliation: Kyoto Pharmaceutical University, Kyoto, Japan. takegami@mb.kyoto-phu.ac.jp
authors.forename: Shigehiko
authors.initials: S
authors.lastname: Takegami
authors.forename: Keisuke
authors.initials: K
authors.lastname: Kitamura
authors.forename: Hiroto
authors.initials: H
authors.lastname: Kawada
authors.forename: Yu
authors.initials: Y
authors.lastname: Matsumoto
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Kitade
authors.forename: Hiroharu
authors.initials: H
authors.lastname: Ishida
authors.forename: Chieyo
authors.initials: C
authors.lastname: Nagata
mesh_terms: D055598:Chemical Phenomena; D002626:Chemistry, Pharmaceutical; D002627:Chemistry, Physical; D004355:Drug Stability; D004655:Emulsions / Q000737:chemistry*; D008055:Lipids / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry; D036103:Nanotechnology; D010168:Palmitates / Q000737:chemistry; D019308:Palmitic Acid / Q000737:chemistry*; D010316:Particle Size; D011136:Polysorbates / Q000737:chemistry; D013395:Sucrose / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry*; D013678:Technology, Pharmaceutical
chemical_list: D004655:Emulsions; D008055:Lipids; D010168:Palmitates; D011136:Polysorbates; D013501:Surface-Active Agents; D019308:Palmitic Acid; D013395:Sucrose