title: Intracellular and extracellular T1 and T2 relaxivities of magneto-optical nanoparticles at experimental high fields.
abstract: This study reports the T(1) and T(2) relaxation rates of rhodamine-labeled anionic magnetic nanoparticles determined at 7, 11.7, and 17.6 T both in solution and after cellular internalization. Therefore cells were incubated with rhodamine-labeled anionic magnetic nanoparticles and were prepared at decreasing concentrations. Additionally, rhodamine-labeled anionic magnetic nanoparticles in solution were used for extracellular measurements. T(1) and T(2) were determined at 7, 11.7, and 17.6 T. T(1) times were determined with an inversion-recovery snapshot-flash sequence. T(2) times were obtained from a multispin-echo sequence. Inductively coupled plasma-mass spectrometry was used to determine the iron content in all samples, and r(1) and r(2) were subsequently calculated. The results were then compared with cells labeled with AMI-25 and VSOP C-200. In solution, the r(1) and r(2) of rhodamine-labeled anionic magnetic nanoparticles were 4.78/379 (7 T), 3.28/389 (11.7 T), and 2.00/354 (17.6 T). In cells, the r(1) and r(2) were 0.21/56 (7 T), 0.19/37 (11.7 T), and 0.1/23 (17.6 T). This corresponded to an 11- to 23-fold decrease in r(1) and an 8- to 15-fold decrease in r(2) . A decrease in r(1) was observed for AMI-25 and VSOP C-200. AMI-25 and VSOP exhibited a 2- to 8-fold decrease in r(2) . In conclusion, cellular internalization of iron oxide nanoparticles strongly decreased their T(1) and T(2) potency.
authors.affiliation: Medizinische Klinik und Poliklinik I, Universitätsklinik Würzburg, Würzburg, Germany. Gert.Klug@uki.at
authors.forename: Gert
authors.initials: G
authors.lastname: Klug
authors.forename: Thomas
authors.initials: T
authors.lastname: Kampf
authors.forename: Steffen
authors.initials: S
authors.lastname: Bloemer
authors.forename: Johannes
authors.initials: J
authors.lastname: Bremicker
authors.forename: Christian H
authors.initials: CH
authors.lastname: Ziener
authors.forename: Andrea
authors.initials: A
authors.lastname: Heymer
authors.forename: Uwe
authors.initials: U
authors.lastname: Gbureck
authors.forename: Eberhard
authors.initials: E
authors.lastname: Rommel
authors.forename: Ulrich
authors.initials: U
authors.lastname: Nöth
authors.forename: Wolfdieter A
authors.initials: WA
authors.lastname: Schenk
authors.forename: Peter M
authors.initials: PM
authors.lastname: Jakob
authors.forename: Wolfgang R
authors.initials: WR
authors.lastname: Bauer
mesh_terms: D000818:Animals; D003287:Contrast Media / Q000737:chemistry / Q000493:pharmacokinetics*; D003911:Dextrans / Q000737:chemistry / Q000493:pharmacokinetics*; D008264:Macrophages / Q000378:metabolism*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles / Q000737:chemistry; D051379:Mice; D017348:Microscopy, Electron, Scanning Transmission; D053758:Nanoparticles / Q000737:chemistry*; D012235:Rhodamines / Q000493:pharmacokinetics; D013054:Spectrophotometry, Atomic; D004113:Succimer / Q000493:pharmacokinetics
chemical_list: D003287:Contrast Media; D003911:Dextrans; D058185:Magnetite Nanoparticles; D012235:Rhodamines; D004113:Succimer; C065507:ferumoxides