Abstract
Background: The increasing use of nanomaterials and nanoproducts has increased the possibility of contamination of the environment, which may have adverse effects on different organisms. The aim of this study was to evaluate the effects of silver nanoparticles on histopathology and gill ultrastructure of zebrafish (Danio rerio) under laboratory conditions. Methods: Zebrafish were exposed to four concentrations of silver nanoparticles (0.0015, 0.00375, 0.0075, and 0.015 mg/l) for a period of 4 days. Gill ultrastructure and histopathological changes were studied using scanning electron microscope and haematoxylin - eosin staining. Results: Exposure to silver nanoparticles significantly (P < 0.001) increased the diameter of gill filaments and secondary lamellae, while silver nanoparticles significantly reduced the length of the secondary gills in zebrafish. Moreover, other changes such as vacuolization, dilated and clubbed tips, hyperplasia, edema, fusion, swelling of mucocytes, hypertrophy, and necrosis were observed. The effects of silver nanoparticles in zebrafish gills were dose dependent. Conclusion: Based on the adverse effects of AgNPs on zebrafish gills, silver nanoparticle solutions can be hazardous pollutants for the environment.
Highlights
Silver nanoparticles (AgNPs) are one of the most increasingly used nanoparticles in consumer applications including bacteriocides, sensors, inks, catalysts [1], nanocomposite films, and ultrafiltration membranes [2]
These findings indicated that the extent of damage to zebrafish gills increased with higher concentration of silver nanoparticles
Gill filaments and primary lamellae appeared normal and mucus free with well-defined secondary lamellae branching from them (Figure 1, A)
Summary
Silver nanoparticles (AgNPs) are one of the most increasingly used nanoparticles in consumer applications including bacteriocides, sensors, inks, catalysts [1], nanocomposite films, and ultrafiltration membranes [2]. 500 tons of nanosilver is produced every year [3] This nanoparticle can be released into the environment from processes such as washing textiles or cosmetics, leaching from consumer products, and industrial wastes [4], and disposal to aquatic ecosystems. Results: Exposure to silver nanoparticles significantly (P < 0.001) increased the diameter of gill filaments and secondary lamellae, while silver nanoparticles significantly reduced the length of the secondary gills in zebrafish Other changes such as vacuolization, dilated and clubbed tips, hyperplasia, edema, fusion, swelling of mucocytes, hypertrophy, and necrosis were observed. Conclusion: Based on the adverse effects of AgNPs on zebrafish gills, silver nanoparticle solutions can be hazardous pollutants for the environment.
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