multivalency

Multivalency is the property of a molecule, ion, or particle to form multiple simultaneous interactions with a target. This occurs when the entity carries multiple binding sites, ligands, or functional groups that engage with several partners at once. Multivalent interactions can arise on a single molecule or via a scaffold that arranges multiple ligands in space. A central consequence is an enhanced overall binding strength, often described in terms of avidity rather than affinity, because binding and unbinding events are correlated.

Avidity increases can be greater than the sum of per-site affinities due to cooperative binding and reduced dissociation rates. The geometry, spacing, and flexibility of the binding motifs strongly influence selectivity and stability.

In biology, antibodies are inherently multivalent (for example, most IgG molecules have two antigen-binding sites) and can engage repetitive epitopes on pathogens or cells. Pathogens may present multiple surface ligands, and lectins often bind multivalently to carbohydrate displays. In chemistry and materials science, multivalent ligands or chelators coordinate several metal centers, and polymers, dendrimers, and nanoparticles can present many copies of a functional group to promote cross-linking or capture.

Applications include vaccine design, targeted drug delivery, and biosensing, where multivalency improves binding strength and specificity. It also informs the development of anti-adhesion therapies and various catalytic and diagnostic platforms.