Determination of water permeability of paramagnetic liposomes of interest in MRI field.
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.
Terreno
Enzo
E
Department of Chemistry, IFM and Molecular Imaging Center, University of Torino, Via P Giuria 7, I-10125 Torino, Italy. enzo.terreno@unito.it
Sanino
Alberto
A
Carrera
Carla
C
Castelli
Daniela Delli
DD
Giovenzana
Giovanni B
GB
Lombardi
Alberto
A
Mazzon
Roberta
R
Milone
Luciano
L
Visigalli
Massimo
M
Aime
Silvio
S
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*
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