Nanoparticle Primary particle size (nm) Zeta potential (mV) Reference Water DMEM, 10% FBS TiO2 11 -8 -10 25 ZnO 13 -15 -5 25 CeO2 8 +15 -10 25 Nanodiamond Unknown -51.66 -23.7 41 Nanodiamond Unknown +42.39 -11.29 41 Nanodiamond Unknown +45.58 -11.93 41

Table 2: Zeta potential of nanoparticles in water and culture medium.