Application of a water-soluble pyridyl disulfide amine linker for use in Cu-free click bioconjugation

Described herein is the design and synthesis of a discrete heterobifunctional PEG-based pyridyl disulfide/amine-containing linker that can be used in the Cu-free click preparation of bioconjugates. The title PEG-based pyridyl disulfide amine linker is a potentially useful reagent for preparing water-soluble disulfide-linked cargos, and that it may be particularly valuable in expanding the field of Cu-free click-based bioconjugations to include reductively labile antibody, polymer, or nanoparticle-based drug conjugates.