Gallium-68-labelled NOTA-oligonucleotides - an optimized method for their preparation

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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 (68Ga) 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 NOTAoligonucleotide bioconjugate was radiolabelled at roomtemperature with purified and pre-concentrated 68Ga 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 51.1MBq/nmol was reached using a 1470-fold molar excess bioconjugate over 68Ga. This study presents a fast, straightforward and reliable protocol for the preparation of 68Ga-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.

Details

Original languageEnglish
Pages (from-to)63-71
Number of pages9
JournalJournal of Labelled Compounds and Radiopharmaceuticals
Volume59
Issue number2
DOIs
Publication statusPublished - 1 Feb 2016

Keywords

  • Gallium-68, oligonucleotides, radiolabelling

ID: 1440507