Combined Biotin-Terpyridine Systems:  A New Versatile Bridge between Biology, Polymer Science and Metallo-supramolecular Chemistry

Biotin, a well-known binding unit for the proteins avidin and streptavidin, was combined with the chelating ligand terpyridine via polymeric and nonpolymeric spacers. An omega-amino-functionalized terpyridyl-poly(ethylene glycol) was prepared and utilized for complex formation with iron(II), nickel(II), and ruthenium(II) ions. The biocompatibility of the complex formation was investigated in aqueous media. Moreover, biotin was functionalized with a methoxy-poly(ethylene glycol) as a model system. The compounds were characterized by UV/vis and NMR spectroscopy as well as MALDI-TOF mass spectrometry. The systems represent a new combination of strong noncovalent binding units from both biology and synthetic supramolecular chemistry.