title: Nonphospholipid fluid liposomes with switchable photocontrolled release.
abstract: We created novel nonphospholipid photosensitive liposomes from a mixture of a monoacylated azobenzene amphiphile (AzoC10N(+)) and cholesterol sulfate (Schol). This system belongs to the family of sterol-enriched nonphospholipid liposomes that were shown to form stable large unilamellar vesicles (LUVs) with enhanced impermeability. Fluid bilayers were successfully prepared from AzoC10N(+)/Schol (25/75 molar ratio) mixtures, and LUVs could be derived at room temperature using standard extrusion methods. The isomerization process of the bilayer-inserted AzoC10N(+) was characterized. Leakage from these liposomes could be induced by the photoconversion of AzoC10N(+) from its trans form to its cis form. This photocontrolled release from fluid liposomes contrasts with the case of phospholipid-based azo-containing liposomes, which are generally required to be in the gel phase to be photosensitive. It is proposed that the very high degree of conformational order of the monoalkylated amphiphile and the tight packing of the hydrophobic core of the AzoC10N(+)/Schol liposomes make them responsive to the presence of the bulky cis azo isomer. Interestingly, the liposome impermeability could be fully restored by the photoisomerization of the cis form back to the trans form, providing a sharp on-and-off control of payload release. In addition, these nonphospholipid liposomes display a very limited passive release. Therefore, it is shown that AzoC10N(+)/Schol LUVs can be used as nanocontainers, whose content can be released by light in a controlled and switchable manner.
authors.affiliation: Department of Chemistry, Center for Self-Assembled Chemical Structures (CSACS), Université de Montréal , C.P. 6128, Succ. Centre Ville, Montréal, Québec, Canada H3C 3J7.
authors.forename: Zhong-Kai
authors.initials: ZK
authors.lastname: Cui
authors.forename: Thida
authors.initials: T
authors.lastname: Phoeung
authors.forename: Pierre-Antoine
authors.initials: PA
authors.lastname: Rousseau
authors.forename: Gaulthier
authors.initials: G
authors.lastname: Rydzek
authors.forename: Qian
authors.initials: Q
authors.lastname: Zhang
authors.forename: C Geraldine
authors.initials: CG
authors.lastname: Bazuin
authors.forename: Michel
authors.initials: M
authors.lastname: Lafleur
mesh_terms: D001391:Azo Compounds / Q000737:chemistry; D002788:Cholesterol Esters / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry*; D015394:Molecular Structure; D055668:Photochemical Processes
chemical_list: D001391:Azo Compounds; D002788:Cholesterol Esters; D008081:Liposomes; C009850:azobenzene; C007045:cholesteryl sulfate