Thanks to their specific structural features and a wide variety of functionalization options, in the last twenty years calixarenes have demonstrated their relevance as scaffolds to design very interesting ligands for biomacromolecules. With the introduction of properly and wisely selected ligating units and epitopes, charged head groups, lipophilic tails, at the upper and at the lower rim of these macrocycles, an impressive number of potent multivalent ligands have been obtained for relevant functions such as the disruption of protein-protein interactions, enzyme and lectin inhibition, nucleic acid recognition and transport into cells, among others. The important results achieved in term of biological activity suggest, for a near future, the possibility to explore the application of some of these derivatives and of others that will come, in nanomedicine and in biomedical fields as new potential drugs and as tools for diagnosis.
