POSTER

Synthesis of multivalent glycoconjugates based on hybrid nanostructured dyes for biomedical and imaging applications

M. Eugenia Pérez-Ojeda,a Beatriz Trastoy,b Inmaculada García-Moreno,a

Jose Luis Chiara*b

a Instituto Química-Física “Rocasolano”, C.S.I.C., Serrano 119, E-28006 Madrid, Spain

b Instituto de Química Orgánica General, C.S.I.C., Juan de la Cierva 3, E-28006 Madrid, Spain

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We have recently described the synthesis of octakis(3-azidopropyl)octasilsesquioxane (1), a hybrid organic-inorganic scaffold containing eight azido groups with a topologically ideal cube-octameric symmetry (Scheme 1).1 Compound 1 is an excellent nanobulding block that can be readily octafunctionalized with a diversity of terminal alkynes by copper(I)-catalyzed 1,3-dipolar azide-alkyne cycloaddition (CuAAC) to provide new functional nanocages keeping a perfect 3-D cubic symmetry.

We have now undertaken the preparation of bifunctional molecules starting from 1. The functionalization of the octasilsequioxane core with both a bio-recognition element (e.g., a peptidic or carbohydrate epitope) and an “active” molecule, such as a fluorescent dye, a magnetic resonance imaging probe, a drug or other functional molecule, is of great interest for its potential applications as bioimaging agent, for vectorized drug transport or for the study of biological receptors. We have studied the monofunctionalization of 1 with an alkyne-substituted boron dipyrromethene (BODIPY) fluorescent dye (Scheme 1). The control of the degree of substitution of the octa-azide core requires both a careful copper-catalyst choice (Figure 1) as well as a judicious selection of the appropriate reaction stoichiometry. After optimizing the monofunctionalization reaction, complete functionalization of the remaining azide groups with an alkyne-tethered carbohydrate derivative afforded a bifunctional fluorescent glyco-POSS 3 (Scheme 1).

Acknowledgements

We thank MICINN (projects CTQ-2006-15515-C02-02/BQU, MAT2007-65778-C02-01, and CTQ2009-14551-C02-02) and Comunidad de Madrid (project S2009/PPQ-1634 “AVANCAT”) for financial support. We also thank MICINN for a FPU predoctoral fellowship to B. T. and C.S.I.C. for a JAE-PREDOC fellowship to M. E. P-O.

Notes and References

1 B. Trastoy, M.E. Pérez-Ojeda, R. Sastre, J.L. Chiara Chem. Eur. J. 2010, 16, 3833-3841.