This study aims to suggest the limits of silver nanoparticle (AgNP) uses for medicinal purpose and was performed to explore the effect of various doses of silver nanoparticle in rats. Four different doses of AgNP (4, 10, 20, and 40 mg/kg) were injected intravenously. For safety evaluation of injected AgNP, body weight, organ coefficient, whole blood count, and biochemistry panel assay for liver function enzyme (AST, ALT, ALP, and GGTP), comet assay, ROS, and histological parameter were performed; 10-12 week old animals were randomly divided into groups of six individuals each for control, and doses of 40, 20, 10, and 4 mg/kg AgNP injected. Significant changes were observed (p < 0.01) in hematological parameters (WBC count, platelets counts, haemoglobin, and RBC count) in the 40 and 20 mg/kg groups. The changes were non-significant in the other groups (4 and 10 mg/kg group). In the 40 mg/kg group, a significant increase was also found in liver function enzymes like ALT and AST (p < 0.01), ALP (p < 0.01), GGTP (p < 0.01), and bilirubin (p < 0.01). ROS in blood serum increased in the high dose group. Tail migration in single cell gel electrophoresis in the 40, 20, 10, 4 mg/kg, and control groups was 34.9, 29.5, 17.8, 5.8, and 0.0 µm, respectively, which indicated damage in the DNA strand in the high dose group. EDXRF showed a ∼ 10-times increase in silver concentration in the 40 mg/kg group and TEM image also showed particle deposition in the 40 mg/kg group. This study indicates that the AgNP in doses (< 10 mg/kg) is safe for biomedical application and has no side-effects, but its high dose (> 20 mg/kg) is toxic.
