Extra Pulmonary Toxicity Assessment of Gold and Silver Nanorods Following Intra Tracheal Instillation in Rats

The gold nanorods (GNRs) and silver nanorods (SNRs) are utilized in various types of industrial and commercial applications. But, there is limited availability of extra pulmonary toxicity data regarding these nanorods. The present investigation evaluated the extra pulmonary toxicity induced by 10 and 25 nm GNRs and SNRs in rats following intra tracheal instillation. The serum biochemical analysis results have shown elevated levels of serum alanine transaminase (ALT) and serum creatinine following 1 day and 1 week post instillation. GNRs have shown greatly increased serum ALT levels at 1 day, 1 week and 1 month post exposure periods compared to SNRs and quartz (QTZ) treated rats. In case of serum creatinine levels, both GNRs and SNRs have shown similar elevated levels. Histopathology studies of rat liver tissues following exposure of GNRs and SNRs displayed that congestion of central vein, shrinkage and ballooning of hepatocytes and lymphocytic infiltration leading to degeneration after 1 week and 1 month post instillation periods. The histopathology of rat kidney tissue was showed tubular dilation, degeneration and necrosis with 10 nm SNRs and 10 nm GNRs after 1 month post instillation period. The 10 nm GNRs and SNRs have shown great changes in serum biochemical analysis and histopathological studies compared to 25 nm test nanorods. These observations suggest the size and dose dependent translocation and extra pulmonary toxicity of both GNRs and SNRs.