Dendritic receptors for binding and transport of oxyanions

Due to their unique structural features and properties dendrimers are ideally suited for use in diagnostic imaging and therapy, transfection, and drug delivery systems.¹ We are especially interested in efficient binding and controlled release of medicinally and biologically relevant anions with dendrimers tailored. In this context poly(propyleneamine)-dendrimers (POPAM) having anion affecting groups at the periphery seems to be very promising. Thus, we could show that urea-functionalized dendrimers are efficient carriers for oxyanions.²

This paper reports the binding behaviour of POPAM-dendrimers having the pH-switchable unit methyl orange at the periphery I. Furthermore POPAM-dendrimers possessing 2,6-diamidopyridine moieties IIa and IIb are investigated. The extractability of the radioactive pertechnetate TcO₄ ^- and the nucleotides AMP, ADP, and ATP with dendrimers are evaluated quantitatively by tracer methods in CHCl₃/H₂O systems. The extraction efficiency is studied in dependence on time, pH, buffer system, dendrimer concentration and generation. A dendritic effect is clearly visible for all dendrimers investigated. Controlled release of anionic guest molecules from the dendrimer host is allowed by alteration the pH.

[1] D.A. Tomalia, A.M. Naylor, W.A Goddart III, Angew. Chem. Int. Ed. Engl. 1990, 29, 138; Y. Kim, S.C. Zimmermann, Curr. Opin. Chem. Biol. 1998, 2, 733; O.A. Matthews, A.N. Shipway, J.F. Stoddart, Prog. Polym. Sci 1998, 23, 1; M. Fischer, F. Vögtle, Angew. Chem. Int. Ed. Engl. 1999, 38, 884; A.W. Bosman, H.M. Janssen, E.W. Meijer, Chem. Rev. 1999, 99, 1665.
[2] H. Stephan, H. Spies, B. Johannsen, L. Klein, F. Vögtle, Chem. Commun. 1999, 1875-1876