title: Cold field emission gun-scanning electron microscopy: a new tool for morphological and ultrastructural analysis of liposomes.
abstract: Liposomes are lipid vesicles largely investigated in the past 30 years as pharmaceutical carriers. In the development of new liposome-based formulations, the study of liposome surface properties remains a crucial step. For this purpose, microscopy techniques can provide useful information, although each such technique suffers from some limitations. Here, we have used cold field emission gun-scanning electron microscopy (cFEG-SEM) to acquire detailed images of liposome surface. In particular, we observed PEGylated and non-PEGylated liposomes in different size ranges. In the case of nanosized liposomes (mean diameter about 200 nm), a morphological evaluation of the whole preparation was obtained. On the other hand, in the case of giant liposomes (mean diameter about 2 microm), it was possible to observe the different surface ultrastructures of the two formulations. In particular, a regular and only slightly wrinkled surface was observed in the case of non-PEGylated liposomes, while a very irregular surface ultrastructure was visible in the case of PEGylated liposomes. This study shows, for the first time, the potential of cFEG-SEM as a new and powerful tool to obtain information on liposome morphology and, at least in the case of giant liposomes, on ultrastructure of the liposome surface.
authors.affiliation: Dipartimento di Chimica Farmaceutica e Tossicologica, Facoltà di Farmacia, Università degli studi di Napoli Federico II, Via Domenico Montesano 49, 80131 Napoli, Italy. gderosa@unina.it
authors.forename: G
authors.initials: G
authors.lastname: De Rosa
authors.forename: M
authors.initials: M
authors.lastname: De Stefano
authors.forename: F
authors.initials: F
authors.lastname: Ungaro
authors.forename: M I
authors.initials: MI
authors.lastname: La Rotonda
mesh_terms: D008051:Lipid Bilayers / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning / Q000379:methods*; D053758:Nanoparticles / Q000737:chemistry; D013499:Surface Properties
chemical_list: D008051:Lipid Bilayers; D008081:Liposomes