Cysteine-Specific F and NIR Dual Labeling of Peptides via Vinyltetrazine Bioorthogonal Conjugation for Molecular Imaging.

Radiolabeled peptides are vital for positron emission tomography (PET) imaging, yet the F-labeling peptides remain challenging due to harsh conditions and time-consuming premodification requirements. Herein, we developed a novel vinyltetrazine-mediated bioorthogonal approach for highly efficient F-radiolabeling of a native peptide under mild conditions. This approach enabled radiosynthesis of various tumor-targeting PET tracers, including targeting the neurofibromin receptor (), the integrin αβ (), and the platelet-derived growth factor receptor β (), with a radiochemical yield exceeding 90%. Preliminary evaluations revealed excellent hydrophilicity across these tracers, with effectively visualizing integrin αβ expression (tumor uptake: 1.57 ± 0.54%ID/g at 2 h). Additionally, we explored the potential for development of PET/near-infrared (NIR) dual-labeling agents using this method. The dual-modality agent enables specificity and colocalized imaging integrin αβ expression (tumor uptake: 1.35 ± 0.24%ID/g at 2 h). Overall, this strategy offers a versatile platform for peptide radiolabeling and dual-modality agent development.