Table 1. Characteristics of three ENPs examined by different physical-chemical methods, such as dynamic light scattering, zeta potential analysis and transmission electron microscopy (TEM), according to Smulders et al.

[12].

	Nanosilver	Nanotitanium dioxide	Nanosilicon dioxide
Function	Biocide	Self-cleaning agent	Scratch resistance
Endotoxin	No	No	No
TEM size (nm)	25 (spherical) to 80–90 (rods)	15	19
Hydrodynamic diameter (nm)	91	386	195
Zeta potential (mV)	−42	−25	−14
Shape	Spheres and rods	Spherical	Spherical