Bioaccumulation of water-borne silver nanoparticles and silver nitrate in striped catfish, Pangasianodon hypophthalmus, fed dietary nucleotides

Recent development in the nanotechnology industry and increase in the number of products manufactured by nanoparticles has inevitably contributed to the discharging of nanomaterials into the aquatic ecosystems. To improve the harmful effects of these toxic materials diverse complements like dietary nucleotides (NT) have been proposed. The effects of dietary NT on silver bioaccumulation in gill and muscle tissues were described after exposure to various concentrations of water-borne silver nanoparticles (AgNPs) and/or silver nitrate (AgNO3) in the present investigation. Specimens of striped catfish, Pangasianodon hypophthalmus, were divided into two groups fed with two different diets (control and NTsupplemented 0.75%) over a period of 10 weeks and were subsequently exposed to various concentrations of AgNPs and AgNO3 under static-renewal conditions for 10 days as follow: 1μg/L AgNPs, 1μg/L AgNO3, 20μg/L AgNPs and 20μg/L AgNO3. After the exposure period, samples of gill and muscle tissue were taken to measure silver bioaccumulation via atomic absorption spectrometry. Silver bioaccumulation in gills was about 5-10 times higher than those measured in the muscles. By increasing silver concentrations in the water, its accumulation in the tissues increased significantly. Generally, AgNO3tended to accumulate more than AgNPs in both tissues and all used concentrations. Fish fed on dietary NT showed lower silver accumulation levels in both tissues; although, the lower accumulation was more clear in gills in comparison to the muscles. It could be concluded that adding NT to the diet of striped catfish could significantly boost the fish defense against silver accumulation, but it is recommended to do some detailed studies to find out its mechanism.