Stoichiometry-focused 18F-labeling of alkyne-substituted oligodeoxynucleotides using azido([18F]fluoromethyl)benzenes by Cu-catalyzed Huisgen reaction

A novel method for 18F-radiolabeling of oligodeoxynucleotides (ODNs) by a Cu-catalyzed Huisgen reaction has been developed by using the lowest possible amount of the precursor biomolecule for the realization of stoichiometry-oriented PET (positron emission tomography) chemistry. Under the optimized cyclization conditions of p- or m-azido([18F]fluoromethyl)benzene and alkyne-substituted ODN (20 nmol) at 40 °C for 15 min in the presence of CuSO4, TBTA [tris((1-benzyl-1H-1,2,3-triazol-4-yl)methyl)amine], and sodium ascorbate (2:1:2), the synthesis of 18F-labeled ODNs with sufficiently high radioactivities of 2.1-2.5 GBq and specific radioactivities of 1800-2400 GBq/μmol have been accomplished for use in animal and human PET studies.