In its 2012 proposed terminology for biologically related polymers, the IUPAC defined a nanoparticle as "a particle of any shape with dimensions in the 1 × 10 and 1 × 10 m range". This definition evolved from one given by IUPAC in 1997.
In another 2012 publication, the IUPAC extends the term to include tubes and fibers with only two dimensions below 100 nm.