Multivalent glycocalixarenes for recognition of biological macromolecules: glycocalyx mimics capable of multitasking

The glycoside cluster effect, a special case of multivalency involving carbohydrates, is a powerful tool exploited by Nature to make relatively weak interactions stronger and more specific. Organic and supramolecular chemists have been applying this concept and are devising a plethora of neo-glycoconjugates which can interfere with a series of pathological events such as infections due to viruses and bacteria, tumour progression and migration, and inflammation processes. In the present Tutorial Review, we will illustrate the factors that make calixarenes, the cyclic oligomers obtained by the condensation of phenols/resorcinols and aldehydes, unique scaffolds for the construction of multivalent glycosylated ligands, individually analysing how structural parameters such as the size, valency, conformation, self-assembling behaviour of the macrocycle and especially the topology of the saccharide presentation in space influence the biological properties. We will not only survey the most significant results obtained to date in the inhibition of carbohydrate binding proteins (lectins), but we will also try to paint a picture of the potential that multivalent glycocalixarenes might have in bionanotechnology and nanomedicine, that are especially related to their combined ability to load cargo and to specifically deliver that cargo to target cells.