title: Determination of water permeability of paramagnetic liposomes of interest in MRI field.
abstract: The water permeability of various liposome membranes has been determined at 298K by measuring the NMR longitudinal water proton relaxation rate of vesicles encapsulating the clinically approved Gd-HPDO3A complex (HPDO3A=10-(2-hydroxypropyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid). Two basic formulations based on DPPC (dipalmitoylphosphatidylcholine) and POPC (palmitoyl-oleylphosphatidylcholine) phospholipids were selected and investigated. Furthermore, the permeability changes caused by the membrane incorporation of amphiphiles like cholesterol and/or metal complexes of interest for designing improved liposome-based MRI contrast agents, were also investigated. The incorporation of cholesterol and metal complexes bearing C18 saturated chains in POPC-based liposomes reduces the water diffusivity across the membrane bilayer. On the contrary, the incorporation of a macrocyclic metal complex bearing four C12 alkylic chains, one for each coordination arm of the ligand, considerably enhances the water permeability in DPPC-based liposomes. Finally, it is reported that the permeability of POPC-based bilayer is increased when the liposomes are subjected to an osmotic stress.
authors.affiliation: Department of Chemistry, IFM and Molecular Imaging Center, University of Torino, Via P Giuria 7, I-10125 Torino, Italy. enzo.terreno@unito.it
authors.forename: Enzo
authors.initials: E
authors.lastname: Terreno
authors.forename: Alberto
authors.initials: A
authors.lastname: Sanino
authors.forename: Carla
authors.initials: C
authors.lastname: Carrera
authors.forename: Daniela Delli
authors.initials: DD
authors.lastname: Castelli
authors.forename: Giovanni B
authors.initials: GB
authors.lastname: Giovenzana
authors.forename: Alberto
authors.initials: A
authors.lastname: Lombardi
authors.forename: Roberta
authors.initials: R
authors.lastname: Mazzon
authors.forename: Luciano
authors.initials: L
authors.lastname: Milone
authors.forename: Massimo
authors.initials: M
authors.lastname: Visigalli
authors.forename: Silvio
authors.initials: S
authors.lastname: Aime
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry; D005682:Gadolinium; D006571:Heterocyclic Compounds; D028581:Lanthanoid Series Elements / Q000737:chemistry*; D008081:Liposomes / Q000737:chemistry*; D008279:Magnetic Resonance Imaging; D009942:Organometallic Compounds / Q000737:chemistry; D010539:Permeability; D010713:Phosphatidylcholines / Q000737:chemistry; D014867:Water / Q000737:chemistry*
chemical_list: D006571:Heterocyclic Compounds; D028581:Lanthanoid Series Elements; D008081:Liposomes; D009942:Organometallic Compounds; D010713:Phosphatidylcholines; C062402:gadoteridol; D014867:Water; D015060:1,2-Dipalmitoylphosphatidylcholine; D005682:Gadolinium; C028694:1-palmitoyl-2-oleoylphosphatidylcholine