A number of different polyvalent scaffolds have been developed in the past. And scaffolds based on various core structures such as dendrimers, sugars, aromatic ring systems or amino acids and peptides have shown promising properties. However, none of these systems combines all the properties of an ideal polyvalent scaffold: rigidity, three dimensional orientation of ligands, defined and tuneable ligand to ligand distances and a defined ligand to scaffold ratio (as well as a cost and resource effective synthesis). Nature has combined these properties in certain virus structures such as the influenza virus, which is recognizing and infecting cells via polyvalent interactions. We would therefore like to mimic these natural structures with rigid scaffolds based on adamantane to construct multivalent conjugates of ligands and contrast agents for tumour imaging.  The choice for adamantane as a rigid scaffold was due to several advantageous properties. Adamantane is rigid, it should permit regioselective functionalization at its bridgehead positions and a lot is known about the metabolism of substituted adamantanes in vivo. From these studies it is known, that most adamantane derivatives are non toxic to humans.

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