Preparation and characterization of stable nano-Ag dispersions for nanotoxicological studies

In spite of the increasing importance of manufactured nano materials, only limited information is available on the behavior of their colloidal suspensions (e.g., agglomeration, aggregation and precipitation) in the media. In this study, we investigated the effects of capping ligand concentrations (e.g. citrate and fetal bovine serum) on the colloidal stability of silver nanoparticle (nano-Ag) in relevant toxicity test media. By monitoring their sedimentation and agglomeration behavior, the optimum conditions for stable colloidal nano-Ag suspensions were found for nanotoxicological studies. The agglomeration and sedimentation kinetics were slowed down as the ligand concentration increased. When citrate concentration in the MHW was increased from 4.54 to 45.45 ([citrate]/[nano-Ag]), the size of the agglomerates was significantly reduced from 178.0 ± 7.0 to 14.7 ± 1.4 nm. On the other hand, reduction of hydrodynamic sizes from 330.3 ± 18.6 to 75.7 ± 9.3 nm were observed when the concentration of FBS in RPMI-1640 media increased from 0.01 to 10%.