Time-Resolved Infrared ATR Measurements of Liposome Transport Kinetics in Human Keratinocyte Cultures and Skin Reveals a Dependence on Liposome Size and Phase State

Abstract

A novel in vitro method for studying the permeation kinetics of superficially applied liposomes or vesicles through layers of human skin or keratinocytes on a solid support is presented, employing attenuated total reflection infrared spectroscopy. The method is applied to investigate transport kinetics of unilamellar vesicles of dimyristoylphosphatidylcholine (DMPC) through cultured human keratinocyte layers and through human skin. We find a strong resemblance of the qualitative features of the permeation kinetics of small unilamellar DMPC vesicles for skin and keratinocytes. Detailed studies of the vesicles transport through keratinocyte layers show that DMPC vesicles with an average diameter of 55 nm can readily permeate through the layer at 37 degrees C with a diffusion constant of D = (4.0 +/- 0.8) x 10(-15) m2/second, whereas larger vesicles of twice that diameter do not permeate at all. In contrast, liposomes containing a chemical permeation enhancer permeate through the layer significantly faster [D = (7.0 +/- 0.5) x 10(-15) m2/second] than the small DMPC vesicles despite their five-times-larger diameter. Moreover, the transport of the DMPC vesicles depends drastically on their phase state. No permeation was observed for small DMPC vesicles at a temperature of 10 degrees C when the lipid is in the crystalline phase state. Our results indicate that keratinocyte culture layers can pose a significant permeation barrier for vesicles. The permeation mechanism can be explained by diffusion of the vesicles through small pores and gaps in the layer, presumably driven by transdermal osmotic gradients.

Lipid Exchange and Transfer on Nanoparticle Supported Lipid Bilayers: Effect of Defects, Ionic Strength, and Size

“…Defect densities in curved membranes, although hypothetical, have been proposed to affect protein binding affinities, 29 2 H NMR evidence strongly suggests that order parameters in lipid bilayers on silica supports in water have a dependence on curvature, 30 and the permeation of cells by vesicles has been found to be dependent on their size (i.e., curvature). 31 ■ EXPERIMENTAL SECTION Materials and Methods. Materials.…”

“…(iv) Curvature of lipids on NPs can affect their packing parameters, defect density, and thus the ability to desorb from the bilayers. Defect densities in curved membranes, although hypothetical, have been proposed to affect protein binding affinities, 2 H NMR evidence strongly suggests that order parameters in lipid bilayers on silica supports in water have a dependence on curvature, and the permeation of cells by vesicles has been found to be dependent on their size (i.e., curvature) …”

Feasibility of Tracking Phospholipid Permeation into Skin Using Infrared and Raman Microscopic Imaging

“…It is possible that the degree of disorder or fusogenicity in POPC versus DMPC vesicles plays a role in the observed differences. Interestingly, IR-ATR measurements have shown that small, unilamellar DMPC vesicles at T4T m permeated full-thickness human skin (Reinl et al, 1995).…”

Surface of Textiles and the Human Skin

“…ATR spectroscopy has been used in the past for investigations on the uptake of cosmetic substances by the skin and by cultures of keratinocytes. Some other techniques for detecting penetrating chemicals like gas-chromatographic analysis may be used, too [15][16][17].…”