title: Structural studies of commercial fat emulsions used in parenteral nutrition.
abstract: In this paper, we demonstrate that by employing a combination of sedimentation field-flow fractionation (sedFFF) and other characterization techniques, such as photon correlation spectroscopy (PCS) and freeze-fracture electron microscopy (EM), it is possible to show that commercial fat emulsions of similar overall chemical compositions not only may exhibit different size distributions but may have different densities as well. A closer look at the density difference between droplet and suspension medium, on the one hand, and the droplet size, on the other, demonstrates that fat emulsions may have structures other than the traditional oil droplet surrounded by a monolayer of surfactant. From our determined and simulated density differences, we propose that these emulsion droplets may have a multilayered surfactant arrangement as well as an inclusion of water vesicles in the oil phase of the emulsion. Freeze-fracture EM observations provide evidence to confirm the existence of such complex structures. These findings are supported by recent EM work from other laboratories, as well as through chemical verification of elevated water contents in the oil droplets of these emulsions.
authors.affiliation: Department of Bioengineering, University of Utah, Salt Lake City 84112.
authors.forename: J
authors.initials: J
authors.lastname: Li
authors.forename: K D
authors.initials: KD
authors.lastname: Caldwell
mesh_terms: D004355:Drug Stability; D004655:Emulsions; D005217:Fat Emulsions, Intravenous / Q000737:chemistry*; D005990:Glycerol / Q000737:chemistry; D008854:Microscopy, Electron; D010288:Parenteral Nutrition; D010316:Particle Size; D010743:Phospholipids; D017785:Photons; D012450:Safflower Oil; D013024:Soybean Oil; D013053:Spectrophotometry; D013501:Surface-Active Agents / Q000737:chemistry
chemical_list: D004655:Emulsions; D005217:Fat Emulsions, Intravenous; D010743:Phospholipids; D013501:Surface-Active Agents; C063336:safflower oil, soybean oil, phospholipid emulsion; D013024:Soybean Oil; D012450:Safflower Oil; D005990:Glycerol