title: Gallium-68-labelled NOTA-oligonucleotides: an optimized method for their preparation.
abstract: One of the most essential aspects to the success of radiopharmaceuticals is an easy and reliable radiolabelling protocol to obtain pure and stable products. In this study, we optimized the bioconjugation and gallium-68 ((68) Ga) radiolabelling conditions for a single-stranded 40-mer DNA oligonucleotide, in order to obtain highly pure and stable radiolabelled oligonucleotides. Quantitative bioconjugation was obtained for a disulfide-functionalized oligonucleotide conjugated to the macrocylic bifunctional chelator MMA-NOTA (maleimido-mono-amide (1,4,7-triazanonane-1,4,7-triyl)triacetic acid). Next, this NOTA-oligonucleotide bioconjugate was radiolabelled at room temperature with purified and pre-concentrated (68) Ga with quantitative levels of radioactive incorporation and high radiochemical and chemical purity. In addition, high chelate stability was observed in physiological-like conditions (37 °C, PBS and serum), in the presence of a transchelator (EDTA) and transferrin. A specific activity of 51.1 MBq/nmol was reached using a 1470-fold molar excess bioconjugate over (68) Ga. This study presents a fast, straightforward and reliable protocol for the preparation of (68) Ga-radiolabelled DNA oligonucleotides under mild reaction conditions and without the use of organic solvents. The methodology herein developed will be applied to the preparation of oligonucleotidic sequences (aptamers) targeting the human epidermal growth factor receptor 2 (HER2) for cancer imaging.
authors.affiliation: Radiobiology Unit, Belgian Nuclear Research Center (SCK•CEN), Mol, Belgium.|Cyclotron Research Center, University of Liège, Liège, Belgium.
authors.forename: Marlies
authors.initials: M
authors.lastname: Gijs
authors.affiliation: Cyclotron Research Center, University of Liège, Liège, Belgium.
authors.forename: Sylvestre
authors.initials: S
authors.lastname: Dammicco
authors.affiliation: Cyclotron Research Center, University of Liège, Liège, Belgium.
authors.forename: Corentin
authors.initials: C
authors.lastname: Warnier
authors.affiliation: Radiobiology Unit, Belgian Nuclear Research Center (SCK•CEN), Mol, Belgium.
authors.forename: An
authors.initials: A
authors.lastname: Aerts
authors.affiliation: Radiobiology Unit, Belgian Nuclear Research Center (SCK•CEN), Mol, Belgium.
authors.forename: Nathalie R E N
authors.initials: NR
authors.lastname: Impens
authors.affiliation: Radiobiology Unit, Belgian Nuclear Research Center (SCK•CEN), Mol, Belgium.|In vivo Cellular and Molecular Imaging Laboratory, Vrije Universiteit Brussel, Brussels, Belgium.
authors.forename: Matthias
authors.initials: M
authors.lastname: D'Huyvetter
authors.affiliation: Cyclotron Research Center, University of Liège, Liège, Belgium.
authors.forename: Marc
authors.initials: M
authors.lastname: Léonard
authors.affiliation: Radiobiology Unit, Belgian Nuclear Research Center (SCK•CEN), Mol, Belgium.
authors.forename: Sarah
authors.initials: S
authors.lastname: Baatout
authors.affiliation: Cyclotron Research Center, University of Liège, Liège, Belgium.
authors.forename: André
authors.initials: A
authors.lastname: Luxen
mesh_terms: D005710:Gallium Radioisotopes / Q000737:chemistry*; D006571:Heterocyclic Compounds / Q000737:chemistry*; D006573:Heterocyclic Compounds, 1-Ring; D009842:Oligopeptides / Q000737:chemistry*; D019275:Radiopharmaceuticals / Q000138:chemical synthesis*
chemical_list: D005710:Gallium Radioisotopes; D006571:Heterocyclic Compounds; D006573:Heterocyclic Compounds, 1-Ring; D009842:Oligopeptides; D019275:Radiopharmaceuticals; C048993:1,4,7-triazacyclononane-N,N',N''-triacetic acid
keywords: DNA; NOTA; bioconjugation; chelator; gallium-68; macrocyclic; molecular imaging; oligonucleotides; positron emission tomography; radiolabelling