title: Chelator free gallium-68 radiolabelling of silica coated iron oxide nanorods via surface interactions.
abstract: The commercial availability of combined magnetic resonance imaging (MRI)/positron emission tomography (PET) scanners for clinical use has increased demand for easily prepared agents which offer signal or contrast in both modalities. Herein we describe a new class of silica coated iron-oxide nanorods (NRs) coated with polyethylene glycol (PEG) and/or a tetraazamacrocyclic chelator (DO3A). Studies of the coated NRs validate their composition and confirm their properties as in vivo T2 MRI contrast agents. Radiolabelling studies with the positron emitting radioisotope gallium-68 (t1/2 = 68 min) demonstrate that, in the presence of the silica coating, the macrocyclic chelator was not required for preparation of highly stable radiometal-NR constructs. In vivo PET-CT and MR imaging studies show the expected high liver uptake of gallium-68 radiolabelled nanorods with no significant release of gallium-68 metal ions, validating our innovation to provide a novel simple method for labelling of iron oxide NRs with a radiometal in the absence of a chelating unit that can be used for high sensitivity liver imaging.
authors: Department of Chemistry, University of Hull, Cottingham Road, Hull, HU6 7RX, UK. s.j.archibald@hull.ac.uk.
authors: Benjamin P
authors: BP
authors: Burke
authors: Neazar
authors: N
authors: Baghdadi
authors: Alicja E
authors: AE
authors: Kownacka
authors: Shubhanchi
authors: S
authors: Nigam
authors: Gonçalo S
authors: GS
authors: Clemente
authors: Mustafa M
authors: MM
authors: Al-Yassiry
authors: Juozas
authors: J
authors: Domarkas
authors: Mark
authors: M
authors: Lorch
authors: Martin
authors: M
authors: Pickles
authors: Peter
authors: P
authors: Gibbs
authors: Raphaël
authors: R
authors: Tripier
authors: Christopher
authors: C
authors: Cawthorne
authors: Stephen J
authors: SJ
authors: Archibald
mesh_terms: D000818:Animals; D005260:Female; D005290:Ferric Compounds / Q000737:chemistry / Q000494:pharmacology; D005710:Gallium Radioisotopes / Q000737:chemistry / Q000494:pharmacology; D006573:Heterocyclic Compounds, 1-Ring / Q000737:chemistry / Q000494:pharmacology; D007553:Isotope Labeling / Q000379:methods*; D051379:Mice; D008819:Mice, Nude; D043942:Nanotubes / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry / Q000494:pharmacology; D049268:Positron-Emission Tomography / Q000379:methods*; D012822:Silicon Dioxide / Q000737:chemistry / Q000494:pharmacology
chemical_list: C520644:1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid; D005290:Ferric Compounds; D005710:Gallium Radioisotopes; D006573:Heterocyclic Compounds, 1-Ring; C000499:ferric oxide; D011092:Polyethylene Glycols; D012822:Silicon Dioxide; C000595209:polyethylene glycol 1000