A dual optical and nuclear imaging reagent for peptide labelling via disulfide bridging

We report a concise approach to a multimodal imaging reagent for peptide labelling via disulfide bridging. The reagent is constructed using a one pot, three component, [3 + 2] cycloaddition of a fluorescent azide with a dithiomaleimide-alkyne, with concomitant incorporation of (125)I. The dithiomaleimide handle then enables site selective conjugation to a disulfide bond of a peptide whilst retaining the key structural bridging functionality, as exemplified on the therapeutic peptide octreotide.