Subchronic oral toxicity evaluation of gold nanoparticles in male and female mice

Abstract

Gold nanoparticles (AuNPs) are biocompatible nanomaterials with potential application in the food industry. The safety of AuNPs oral consumption remains inconclusive, and information on possible long-term toxicity is limited. The current study aimed to evaluate the subchronic oral toxicity of AuNPs in male and female Institute of Cancer Research (ICR) mice. Citrate-coated spherical AuNPs with 53 nm diameters were prepared and orally administered to the mice. No mortality or clinical abnormalities were observed following daily administration of AuNPs at the dosages of 0.2, 2, and 20 mg/kg for 90 days. There was no significant difference in body weight or the relative organs' weights between the control and AuNPs-treated mice. No gross abnormalities or histopathological changes were observed except that the male mice treated with high dose (20 mg/kg AuNPs) showed minor infiltration in the kidneys, and female mice showed a reduced A/G ratio and elevated platelet indices. Overall, the 90-day long-term oral consumption of AuNPs did not cause significant toxicity in mice.

Keywords: Chronic toxicity; Gold; Nanoparticle; Oral; Tissue histopathology.

Figure 1

Characterization of colloidal gold nanoparticles. (a) TEM image shows the AuNPs of spheric shape with a core size of 25.4 ± 6.1 nm, (b) The colloidal AuNPs solution has an absorption band at λmax = 523 nm in the UV-vis spectrum, (c) The citrate-encapsulated AuNPs have a mean diameter of 52.9 ± 27 nm in DLS analysis, and (d) The colloidal AuNPs solution shows zeta potential of −41.7 mV at pH 2.5 and electrical conductivity of 1.342 mS/cm.

Figure 2

Mean body weight of (a) male and (b) female ICR mice orally treatment with AuNPs for 90 days. No significant change of weights on the AuNPs treatment.

Figure 3

Representative photographs of liver and kidney from male and female ICR mice after orally treatment with AuNPs for 90 days. No apparent morphological alteration on AuNPs treatment at the dosages of 0.2, 2 and 20 mg/kg body weight. Scale bar = 1 cm.

Figure 4

Effects of oral administration of AuNPs for 90 days on liver and renal histology in male and female mice. (a) H&E staining shows no histopathological lesion in liver and kidney, except for a slight inflammatory infiltration of the male mice kidney cells (indicated by black arrows) on treatment with high dosage of AuNPs. (b) Sirius red staining of hepatic and renal tissues shows no obvious interstitial fibrosis in male and female mice treatment with AuNPs. Scale bar = 50 μm.