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Preparation of 18F-labeled peptides using the copper(I)-catalyzed azide-alkyne 1,3-dipolar cycloaddition


An optimized procedure for preparing fluorine-18 (18F)-labeled peptides by the copper-catalyzed azide-alkyne 1,3-dipolar cyloaddition (CuAAC) is presented here. The two-step radiosynthesis begins with the microwave-assisted nucleophilic 18F-fluorination of a precursor containing a terminal p-toluenesulfonyl, terminal azide and polyethylene glycol backbone. The resulting 18F-fluorinated azide-containing building block is coupled to an alkyne-decorated peptide by the CuAAC. The reaction is accelerated by the copper(I)-stabilizing ligand bathophenanthroline disulfonate and can be performed in either reducing or nonreducing conditions (e.g., to preserve disulfide bonds). After an HPLC purification, 18F-labeled peptide can be obtained with a 31 ± 6% radiochemical yield (n = 4, decay-corrected from 18F-fluoride elution) and a specific activity of 39.0 ± 12.4 Ci μmol−1 within 77 ± 4 min.

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Figure 1
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Figure 4: Deconvoluted mass spectrum of crude 4.
Figure 5
Figure 6: Deconvoluted mass spectrum demonstrating the enrichment of 4 from 1.


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We thank S. Williams and J.L. Sutcliffe for critical reading of the manuscript and their valuable comments; C. Quan and J. Tom for the peptide synthesis; and J. Tinianow for general assistance with radiolabeling and product characterization.

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H.S.G. and J.M. performed the work and wrote the manuscript.

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Correspondence to Jan Marik.

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The authors declare no competing financial interests.

Supplementary information

Supplementary Methods

Solid phase extraction (SPE) as a replacement for the HPLC purification of 18F-labeled peptides (DOC 33 kb)

Supplementary Table 1

The ascorbate-based and ascorbate-free CuAAC were each tested in varied reaction conditions. (DOC 152 kb)

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Gill, H., Marik, J. Preparation of 18F-labeled peptides using the copper(I)-catalyzed azide-alkyne 1,3-dipolar cycloaddition. Nat Protoc 6, 1718–1725 (2011).

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