Labeling of an antisense oligonucleotide with [(18)F]FPy5yne

Area of Science:

• Radiochemistry
• Molecular Biology
• Biomedical Imaging

Background:

• Functional imaging of gene expression in vivo using fluorine-18 ((18)F) is hindered by long reaction times for labeling nucleic acid probes.
• Existing methods face challenges due to the short half-life of (18)F (109.8 minutes) and complex labeling protocols.

Purpose of the Study:

• To develop a faster and more efficient method for radiolabeling oligodeoxyribonucleotides with (18)F for in vivo gene expression imaging.
• To synthesize and utilize a prosthetic group for copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) radiolabeling.

Main Methods:

• Synthesized the prosthetic group 2-"[(18)F]fluoro-3-(hex-5-ynyloxy)pyridine" ([(18)F]FPy5yne).
• Coupled [(18)F]FPy5yne to a 5'-azide-modified oligodeoxyribonucleotide antisense to mdr1 mRNA using CuAAC reaction.
• Utilized tris(benzyltriazolylmethyl)amine as a Cu(I)-stabilizing ligand and 2,6-lutidine.

Main Results:

• Achieved radiolabeling of the DNA probe with (18)F.
• Obtained non-decay corrected yields of 3.9% +/- 0.5% (n=3) and decay-corrected yields of 24.6% +/- 0.5%.
• The shortest preparation time from synthesis start was 276 minutes.

Conclusions:

• Demonstrated the feasibility of using the [(18)F]FPy5yne prosthetic group for radiolabeling DNA with (18)F.
• The developed method offers a potential advancement for in vivo gene expression imaging by overcoming labeling time constraints.
• Further optimization may enhance yields and reduce preparation times for clinical translation.