title: Fluorescent magnetoliposomes as a platform technology for functional and molecular MR and optical imaging.
abstract: Here, we present a detailed characterisation of rhodamine B-containing magnetoliposomes (FLU-ML), emphasising the dependence of their fluorescence properties on the presence of iron oxide cores, and the molar fraction of the fluorophore. The magnetoliposome types used exist as colloidally stable, negatively charged clusters with an average hydrodynamic diameter of 95 nm. The molar rhodamine B fractions were 0.67 % and 1.97 %. Rhodamine B normalised fluorescence, quantum yields and fluorescence lifetimes were substantially reduced by inner filter effects as the magnetoliposome concentration is increased, by increasing molar rhodamine B fraction, and by quenching originating from the iron oxide cores. MR relaxometry at 3 T revealed extremely high r2 relaxivities (440 to 554 s-1mM-1) and moderately high r1 values (2.06 to 3.59 s-1mM-1). Upon incubating human prostate carcinoma (PC-3) cells with FLU-ML, a dose-dependent particle internalisation was found by MR relaxometry. In addition, the internalised FLU-ML were clearly visible by fluorescence microscopy. At the FLU-ML concentrations used (up to 3 × 10³ M Fe) cell viability was not substantially impaired. These results provide valuable insights on the fluorescence properties of bimodal magnetoliposomes and open promising perspectives for the use of these materials as a platform technology for advanced functional and molecular MR and optical imaging applications.
authors.affiliation: Department of Experimental Molecular Imaging, RWTH Aachen University, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Hodenius
authors.forename: Christian
authors.initials: C
authors.lastname: Würth
authors.forename: Jabadurai
authors.initials: J
authors.lastname: Jayapaul
authors.forename: John E
authors.initials: JE
authors.lastname: Wong
authors.forename: Twan
authors.initials: T
authors.lastname: Lammers
authors.forename: Jessica
authors.initials: J
authors.lastname: Gätjens
authors.forename: Susanne
authors.initials: S
authors.lastname: Arns
authors.forename: Natascha
authors.initials: N
authors.lastname: Mertens
authors.forename: Ioana
authors.initials: I
authors.lastname: Slabu
authors.forename: Gergana
authors.initials: G
authors.lastname: Ivanova
authors.forename: Jörg
authors.initials: J
authors.lastname: Bornemann
authors.forename: Marcel De
authors.initials: MD
authors.lastname: Cuyper
authors.forename: Ute
authors.initials: U
authors.lastname: Resch-Genger
authors.forename: Fabian
authors.initials: F
authors.lastname: Kiessling
mesh_terms: D000042:Absorption; D000230:Adenocarcinoma / Q000473:pathology; D045744:Cell Line, Tumor / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D002470:Cell Survival; D003102:Colloids; D003287:Contrast Media / Q000008:administration & dosage / Q000032:analysis* / Q000737:chemistry; D031541:Fluorescence Resonance Energy Transfer; D005456:Fluorescent Dyes / Q000008:administration & dosage / Q000032:analysis* / Q000737:chemistry; D006801:Humans; D057446:Hydrodynamics; D007700:Kinetics; D008081:Liposomes / Q000008:administration & dosage / Q000737:chemistry / Q000648:ultrastructure; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles / Q000008:administration & dosage / Q000032:analysis* / Q000737:chemistry; D008297:Male; D008856:Microscopy, Fluorescence / Q000379:methods*; D053769:Nanocapsules / Q000008:administration & dosage / Q000032:analysis* / Q000737:chemistry; D010714:Phosphatidylethanolamines; D011471:Prostatic Neoplasms / Q000473:pathology; D012235:Rhodamines / Q000008:administration & dosage / Q000032:analysis* / Q000737:chemistry
chemical_list: D003102:Colloids; D003287:Contrast Media; D005456:Fluorescent Dyes; D008081:Liposomes; D058185:Magnetite Nanoparticles; D053769:Nanocapsules; D010714:Phosphatidylethanolamines; D012235:Rhodamines; C029773:rhodamine B; C018525:1,2-dimyristoylphosphatidylethanolamine