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Chemoselective hydrazone formation between HYNIC-functionalized peptides and (18)F-fluorinated aldehydes
Kjerstin Bruus-Jensen1, Thorsten Poethko, Margret Schottelius
1Department of Nuclear Medicine, Klinikum rechts der Isar, Technischen Universität München, D-81675 Munich, Germany.
A new two-step radiolabeling strategy uses hydrazone formation for (18)F-fluorinated peptides, enabling quantitative PET imaging. This method is fast, versatile, and achieves high yields under mild conditions.
Area of Science:
- Radiochemistry
- Nuclear Medicine
- Peptide Chemistry
Background:
- Increasing demand for (18)F-fluorinated peptides for PET imaging.
- Need for efficient and reliable radiolabeling strategies.
Purpose of the Study:
- Develop a chemoselective two-step (18)F-labeling strategy.
- Evaluate hydrazone formation for peptide radiolabeling.
- Assess the stability of labeled peptides.
Main Methods:
- Preparation of 4-[(18)F]fluorobenzaldehyde ([(18)F]FB-CHO).
- Hydrazone formation between [(18)F]FB-CHO and HYNIC-functionalized peptides.
- Optimization of labeling conditions (pH, precursor concentration, temperature).
- Stability studies in aqueous solution and mouse blood.
Main Results:
- [(18)F]FB-CHO prepared with high radiochemical yield.
- Optimal labeling yields of 85% achieved at 70°C for 10 min.
- Labeling products stable at pH 7.5; slow decomposition in acidic media.
- No detectable degradation in mouse blood within 30 min post-injection.
Conclusions:
- Chemoselective hydrazone formation is a fast and straightforward radiolabeling method.
- Achieves high yields under mild acidic conditions.
- Versatile strategy applicable to various radionuclides and peptide precursors.
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