title: Assessment of fluidity of different invasomes by electron spin resonance and differential scanning calorimetry.
abstract: The aim of this study was to investigate the influence of membrane-softening components (terpenes/terpene mixtures, ethanol) on fluidity of phospholipid membranes in invasomes, which contain besides phosphatidylcholine and water, also ethanol and terpenes. Also mTHPC was incorporated into invasomes in order to study its molecular interaction with phospholipids in vesicular membranes. Fluidity of bilayers was investigated by electron spin resonance (ESR) using spin labels 5- and 16-doxyl stearic acid and by differential scanning calorimetry (DSC). Addition of 1% of a single terpene/terpene mixture led to significant fluidity increase around the C16 atom of phospholipid acyl chains comprising the vesicles. However, it was not possible to differentiate between the influences of single terpenes or terpene mixtures. Incorporation of mTHPC into the bilayer of vesicles decreased fluidity near the C16 atom of acyl chains, indicating its localization in the inner hydrophobic zone of bilayers. These results are in agreement with DSC measurements, which showed that terpenes increased fluidity of bilayers, while mTHPC decreased fluidity. Thus, invasomes represent vesicles with very high membrane fluidity. However, no direct correlation between fluidity of invasomes and their penetration enhancing ability was found, indicating that besides fluidity also other phenomena might be responsible for improved skin delivery of mTHPC.
authors.affiliation: Department of Pharmaceutical Technology, Faculty of Biology and Pharmacy, Friedrich Schiller University Jena, Lessingstrasse 8, 07743 Jena, Germany. ninadragicevic@hotmail.com
authors.forename: Nina
authors.initials: N
authors.lastname: Dragicevic-Curic
authors.forename: Manfred
authors.initials: M
authors.lastname: Friedrich
authors.forename: Silvia
authors.initials: S
authors.lastname: Petersen
authors.forename: Dietrich
authors.initials: D
authors.lastname: Scheglmann
authors.forename: Dennis
authors.initials: D
authors.lastname: Douroumis
authors.forename: Winfried
authors.initials: W
authors.lastname: Plass
authors.forename: Alfred
authors.initials: A
authors.lastname: Fahr
mesh_terms: D002152:Calorimetry, Differential Scanning; D055598:Chemical Phenomena; D004337:Drug Carriers / Q000008:administration & dosage / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D000431:Ethanol / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D008081:Liposomes; D008560:Membrane Fluidity / Q000187:drug effects*; D008652:Mesoporphyrins / Q000008:administration & dosage / Q000737:chemistry*; D010316:Particle Size; D014677:Pharmaceutical Vehicles / Q000737:chemistry; D010713:Phosphatidylcholines / Q000737:chemistry; D017319:Photosensitizing Agents / Q000008:administration & dosage / Q000737:chemistry*; D013729:Terpenes / Q000737:chemistry
chemical_list: D004337:Drug Carriers; D008081:Liposomes; D008652:Mesoporphyrins; D014677:Pharmaceutical Vehicles; D010713:Phosphatidylcholines; D017319:Photosensitizing Agents; D013729:Terpenes; D000431:Ethanol; C072269:temoporfin