Photoconjugation of 3-azido-5-nitrobenzyl-[18F]fluoride to an oligonucleotide aptamer

Photoconjugation techniques are well established in biochemistry and molecular biology applications. We report here the first application of photoconjugation to label an oligonucleotide with positron emitting fluorine-18. ANBF, 3-azido-5-nitrobenzyl fluoride, was tagged with fluorine-18 in 30–50% yield from the corresponding tosylate. The HPLC purified [18F]ANBF was photochemically conjugated to a hexylamine modified 15-base, single stranded, DNA aptamer with up to 20% radiolabeling efficiency, based on starting [18F]ANBF. Separation by gel exclusion chromatography and HPLC analysis of the DNA fractions indicated that the benzyl fluoride was covalently bound to the aptamer. The total reaction time from the start of radiosynthesis was 135 min. Based on these results, the feasibility to photolabel oligonucleotide molecules with fluorine-18 labeled arylazides for PET applications has been established. Copyright © 2002 John Wiley & Sons, Ltd.