The term does not refer to a specific mechanism, as recommended

by IUPAC: https://goldbook.iupac.org/

The correct words for basic mechanisms remain: "precipitation" or "germination". Then one can describe the size distribution of neoformed phases.

A large community use the term "nanopreocipitation" for precipitation processes leading to a majority of "nanocomposite" = of nanometric size (10-9 m).

This is especially usefull for synthesis of particles and encapsulation, for example of drugs.

See ref: Int. Journal of Pharm. Vol. 532, 1, 2017, 66-81.

In drug delivery, the method of producing polymeric nanoparticles (solvent displacement method) discovered by Fessi et al. in 1989 is also called nanoprecipitation. (https://www.sciencedirect.com/science/article/abs/pii/0378517389902810)

The method briefly consists of solubilising the polymer and the active to be encapsulated in a miscible solvent (for example acetone, or ethanol), and surfactants and preservatives in the aqueous phase. The organic phase is gradually added to the aqueous phase under agitation, resulting in the "precipitation" of nanoparticles during solvation of the polymer, stabilised with surfactant to prevent their aggregation into larger particles. The last step is to purify and remove the organic solvent during the hardening process of the nanoparticles, to remove active and excipients out of the nanoparticles.

"Nanoprecipitation" refers to a nanoparticle formation process in which soluble precursors are precipitated at the nanoscale in the presence of a stabilizing agent. This process is often used to produce polymer or metal nanoparticles.

In general, nanoprecipitation involves dissolving precursors in an organic solvent and then adding a stabilizing agent that promotes nanoparticle formation. The nanoparticles are then formed by precipitation from the solution, usually using a rapid-mix or microfluidic method.

This process can be used to produce nanoparticles with controlled size and shape by adjusting precipitation conditions such as precursor concentration, solution composition, temperature, pH, and agitation speed. Nanoprecipitation is a common method of producing nanoparticles in the materials industry and is also used in nanotechnology research.