chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds made of atoms, molecules and ions ...

, polyvalency (or polyvalence, multivalency) is the property of

chemical species A chemical species is a chemical substance or ensemble composed of chemically identical molecular entity, molecular entities that can explore the same set of molecular energy levels on a characteristic or delineated time scale. These energy levels ...

(generally

atom Every atom is composed of a nucleus and one or more electrons bound to the nucleus. The nucleus is made of one or more protons and a number of neutrons. Only the most common variety of hydrogen has no neutrons. Every solid, liquid, gas, and ...

s or

molecule A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bioch ...

s) that exhibit more than one valence by forming multiple

chemical bonds A chemical bond is a lasting attraction between atoms or ions that enables the formation of molecules and crystals. The bond may result from the electrostatic force between oppositely charged ions as in ionic bonds, or through the sharing of ...

(Fig. 1). A bivalent species can form two bonds; a trivalent species can form three bonds; and so on. The principle of polyvalency also applies to larger species, such as

antibodies An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the ...

, medical drugs, and even

nanoparticle A nanoparticle or ultrafine particle is usually defined as a particle of matter that is between 1 and 100 nanometres (nm) in diameter. The term is sometimes used for larger particles, up to 500 nm, or fibers and tubes that are less than 1 ...

s surface-functionalized with ligands, like

spherical nucleic acids Spherical nucleic acids (SNAs) are nanostructures that consist of a densely packed, highly oriented arrangement of linear nucleic acids in a three-dimensional, spherical geometry. This novel three-dimensional architecture is responsible for many o ...

, which can show enhanced or cooperative binding compared to their monovalent counterparts. Nanoparticles with multiple

nucleic acid Nucleic acids are biopolymers, macromolecules, essential to all known forms of life. They are composed of nucleotides, which are the monomers made of three components: a 5-carbon sugar, a phosphate group and a nitrogenous base. The two main cl ...

strands on their surfaces (e.g., DNA) can form multiple bonds with one another by DNA hybridization to form hierarchical assemblies, some of which are highly crystalline in nature.Macfarlane, R. J.; et al. (2011). "Nanoparticle Superlattice Engineering with DNA". Science. 334 (6053): 204–08
doi:10.1126/science.1210493

References

{{Reflist Chemical properties Chemical bonding Dimensionless numbers of chemistry