Sub-chronic dermal toxicity of silver nanoparticles in guinea pig: special emphasis to heart, bone and kidney toxicities

Silver nanoparticles [Ag NPs] have been widely used as new potent antimicrobial agents in cosmetic and hygienic products. Present study compares the tissue levels of Ag NPs in different organs of Guinea Pigs quantitatively after dermal application and analysis the morphological changes and pathological abnormalities on the basis of the Ag NPs tissue levels. Before toxicological assessments, the size of colloidal nanosilver was recorded by X-Ray Diffraction and Transmission Electron Microscope tests and the sizes of samples were recorded in sizes less than 100 nm. For toxicological evaluation, male guinea pigs were exposed to three concentrations of Ag NPs [100, 1000 and 10000 ppm] according to acute pretests for further assessments in subchronic model in a period of 13 weeks. A close correlation between dermal exposure and tissue levels of Ag NPs was found [p < 0.05] and tissue uptakes happened in dose dependent manner with the following ranking: kidney>muscle>bone>skin>liver>heart >spleen. In histopathological studies, severe proximal convoluted tubule degeneration and distal convoluted tubule were seen in the kidneys of the middle and high-dose animals. Separated lines and marrow space narrow were determined as two major signs of bone toxicities which observed in three different dose levels of Ag NPs. Increased dermal dose of Ag NPs caused cardiocyte deformity, congestion and inflammation. The three different Ag NPs concentration gave comparable results for several endpoints measured in heart, bone and kidney, but differed in tissue concentrations and the extent of histopathological changes. It seems that Ag ions could be detected in different organs after dermal exposure, which has the potential to provide target organ toxicities in a time and dose dependent manner

Toxicity assessment of nanosilver wound dressing in Wistar rat

Antibiotic resistance to microorganisms is one of the major problems faced in the field of wound care in burns patients. Silver nanoparticles have come up as potent antimicrobial agent and are being evaluated in diverse medical applications ranging from silver based dressings to silver coated medical devices. We aimed in present study to test the release of nanosilver from nanosilver wound dressing and compare the dermal and systemic toxicity of nanosilver dressings in a repeated dose [21 days] model. Under general anesthesia, a limited standard 2nd degree burns were provided on the back of each rat in all treatment, negative control [simple dressing] and 5% silver nitrate groups, each contained 5 male wistar rats. According to the analysis made by atomic absorption spectrometry, the wound dressings released 0.599 +/- 0.083 ppm of nanosilver during first 24 hrs of study. Daily observations were recoded and wounds were covered with new dressings each 24 hrs. Burn healing was observed in nanosilver wound dressing group in shorter time periods than the control groups. In toxicity assessment, this dressing didn't cause any hematological and histopathological abnormalities in treatment group but biochemical studies showed significant rise of plasma transaminase [ALT] at the endpoint [21 days] of the study [P=0.027]. Portal mononuclear lymphoid and polymorphonuclear leukocyte infiltrations in three to four adjacent foci were recognized around the central hepatic vein in treatment group. Mild hepatotoxic effects of nanosilver wound dressing in wistar rat emphasize the necessity of more studies on toxicity potentials of low dose nanosilver by dermal applications