Abstract
In this study we use the combination of super resolution optical microscopy and raster image correlation spectroscopy (RICS) to study the mechanism of action of liposomes as transdermal drug delivery systems in human skin. Two different compositions of liposomes were applied to newly excised human skin, a POPC liposome and a more flexible liposome containing the surfactant sodium cholate. Stimulated emission depletion microscopy (STED) images of intact skin and cryo-sections of skin treated with labeled liposomes were recorded displaying an optical resolution low enough to resolve the 100 nm liposomes in the skin. The images revealed that virtually none of the liposomes remained intact beneath the skin surface. RICS two color cross correlation diffusion measurements of double labeled liposomes confirmed these observations. Our results suggest that the liposomes do not act as carriers that transport their cargo directly through the skin barrier, but mainly burst and fuse with the outer lipid layers of the stratum corneum. It was also found that the flexible liposomes showed a greater delivery of the fluorophore into the stratum corneum, indicating that they functioned as chemical permeability enhancers.
Highlights
Successful transdermal drug delivery is hindered by the inability of most drugs to penetrate the skin barrier at therapeutically beneficial rates [1, 2]
We have investigated the penetration of POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocoline) large unilamellar vesicles (LUVs) and a flexible vesicle (FLUVs) in human skin using CC-raster image correlation spectroscopy (RICS) of two color fluorescently labeled liposomes and Stimulated emission depletion microscopy (STED) microscopy to investigate whether the intact vesicles penetrate into the skin or if they break upon contact with the skin
Intact skin samples labelled from the stratum corneum (SC) side with free dye before sectioning were investigated using STED
Summary
Successful transdermal drug delivery is hindered by the inability of most drugs to penetrate the skin barrier at therapeutically beneficial rates [1, 2]. Very few drugs can cross the skin barrier, and permeability enhancers are needed in order to facilitate transdermal delivery. To advance the development of efficient permeability enhancers, a thorough knowledge of each enhancer’s efficiency and mechanism of action is needed. One of the lipid vesicle candidates for transdermal drug delivery is liposomes or large unilamellar vesicles (LUVs). They are widely used in the cosmetic industry and have been proposed as vehicles to transport and deliver drugs through the skin barrier [7,8,9].
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
