title: Environmental Scanning Electron Microscope Imaging of Vesicle Systems.
abstract: The structural characteristics of liposomes have been widely investigated and there is certainly a strong understanding of their morphological characteristics. Imaging of these systems, using techniques such as freeze-fracturing methods, transmission electron microscopy, and cryo-electron imaging, has allowed us to appreciate their bilayer structures and factors which can influence this. However, there are few methods which all us to study these systems in their natural hydrated state; commonly the liposomes are visualized after drying, staining, and/or fixation of the vesicles. Environmental Scanning Electron Microscopy (ESEM) offers the ability to image a liposome in its hydrated state without the need for prior sample preparation. Within our studies we were the first to use ESEM to study liposomes and niosomes and we have been able to dynamically follow the hydration of lipid films and changes in liposome suspensions as water condenses on to, or evaporates from, the sample in real time. This provides insight into the resistance of liposomes to coalescence during dehydration, thereby providing an alternative assay of liposome formulation and stability.
authors.affiliation: Strathclyde Institute of Pharmacy and Biomedical Sciences, Glasgow, G4 ORE, Scotland. yvonne.perrie@strath.ac.uk.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Perrie
authors.affiliation: School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, B4 7ET, UK.
authors.forename: Habib
authors.initials: H
authors.lastname: Ali
authors.affiliation: School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, B4 7ET, UK.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Kirby
authors.affiliation: School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, B4 7ET, UK.
authors.forename: Afzal U R
authors.initials: AU
authors.lastname: Mohammed
authors.affiliation: School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, B4 7ET, UK.
authors.forename: Sarah E
authors.initials: SE
authors.lastname: McNeil
authors.affiliation: School of Pharmacy and Chemistry, Kingston University, London, KT1 2EE, UK.
authors.forename: Anil
authors.initials: A
authors.lastname: Vangala
mesh_terms: D000941:Antigens / Q000378:metabolism; D002412:Cations; D004247:DNA / Q000378:metabolism; D021621:Imaging, Three-Dimensional; D008051:Lipid Bilayers / Q000737:chemistry; D008081:Liposomes / Q000648:ultrastructure*; D008855:Microscopy, Electron, Scanning / Q000379:methods*; D004364:Pharmaceutical Preparations / Q000737:chemistry; D010713:Phosphatidylcholines / Q000737:chemistry; D010714:Phosphatidylethanolamines / Q000737:chemistry
chemical_list: D000941:Antigens; D002412:Cations; D008051:Lipid Bilayers; D008081:Liposomes; D004364:Pharmaceutical Preparations; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; C094877:dioleoyl phosphatidylethanolamine; D004247:DNA; C028694:1-palmitoyl-2-oleoylphosphatidylcholine
keywords: ESEM analysis; Lipoplexes; Liposomes; Niosomes; Non-ionic surfactant vesicles; Surfactant vesicles