Nanotoxicology: The impacts of 5 nm silver nanoparticles on protein synthesis of rainbow trout (oncorhynchus mykiss)

Abstract

Silver nanoparticles (nAg) are becoming increasingly prevalent in consumer products due to their unique physicochemical properties. This excessive usage is causing nanoparticulate waste to end up in the water column with the potential to affect aquatic organisms. Previous research has shown damaging effects of engineered nanomaterials (ENMs) on various fish species with the current study aimed to identify the impacts of polyvinyl pyrrolidone (PVP) capped 5 nm silver nanoparticles on biochemical stress indicators and rates of protein synthesis in rainbow trout (Oncorhynchus mykiss). Fish were exposed to 100 μg L-1 nAg or 0.22 μg L-1 AgNO3 for 48 hours and tissue samples taken. Biological endpoints analyzed included hematocrit, gill sodium potassium ATPase, heart acetylcholinesterase, and cortisol and malondialdehyde content. Fractional rates of protein synthesis were determined by flooding dose method modified to use a stable phenylalanine isotope tracer. No significant differences were observed between treatment groups for any of the biologically relevant endpoints nor protein synthesis rates, although a decreasing trend was observed for sodium potassium ATPase activity in nAg-exposed fish. Results suggest that rainbow trout exposed to silver ENMs for 48 hours at the environmentally relevant point-source exposure concentration tested are not expressing signs of significant damage nor exhibiting impaired metabolism indicating that under short term conditions 5 nm PVP-capped nAg at 100 μg L-1 is not acutely toxic. These findings are disputable as previous research has demonstrated the toxic effects of ENMs on fish physiology, including on the endpoints analyzed in this study. These results should encourage further research into longer exposure durations and investigating other potential sublethal effects.