In vitro assessment of the toxicity of small silver nanoparticles and silver ions to the red blood cells

This work reports the toxicity of small silver nanoparticles (nanoAg, 20 nm) and silver ions (Ag⁺) to the red blood cells with the silver concentration level of 10⁻⁶ g/mL. Results show that red blood cells (RBCs) start hemolysis when treated by nanoAg of 1.5 × 10⁻⁵ g/mL or Ag⁺ of 2.9 × 10⁻⁷ g/mL. A low ATPase activity of 30% has been observed after RBCs being treated with Ag⁺ of 2.6 × 10⁻⁷ g/mL, while the nanoAg does not obviously affect the ATPase activity. In molecular level, Ag⁺ is more toxic to the amino acid residues than nanoAg according to the change of fluorescence characteristics of hemoglobin (Hb). However, the nanoAg has been found to be more toxic than Ag⁺ to the secondary structure of Hb in terms of the loss of α-helix content.