Table 1 Differences between environmental and manufactured nanoparticles

Size

≤50 nm (≤100 nm: ultrafine)

1–100 nm (biomedical nanoparticles can be larger than 100 nm)

Dimensions

Two or three dimensions are on the nanoscale

Three dimensions are on the nanoscale (nano-objects with one and two nanoscale dimensions are called nanoplates and nanofibers, respectively)

Names

Nanoparticles, fibrous nanoparticles

Nanoparticles, nanospheres, nanotubes, nanorods, nanofibers, nanowires, nanoropes, nanosheets, nanoeggs, nanoliposomes, dendrimers, etc.

Components

Carbon soot, hydrocarbons (alkanes), heavy metals, sulfur

Carbon (fullerene, nanotube), metal oxide (TiO₂, ZnO), CdSe, metalloids, transition metals, polymers

Sources

Automobile exhaust, friction, catalysts

Production of nanomaterials, cosmetics, friction