BACKGROUND: Application of green chemistry to the synthesis of nanomaterials is of vital importance in medicinal and technological aspects. Recently, synthesis of silver nanoparticles using plants and marine macro algae to adapt this approach to the environment, has become  more popular. Objectives: The purpose of this study is biological synthesis of silver nanoparticles using seaweed, Sargassum angustifolium, and determining its toxicity in common carp. Methods: First, synthesis of silver nanoparticles using Sargassum algae was conducted and then acute toxicity of these silver nanoparticles was investigated at static renewal condition during 96 hours in common carp according to standard methods (1998) OECD. Results: TEM analysis showed that the average size of the bionanoparticles was found to be 32.54 nm and spherical in shape. The toxicity results showed that the LC50 at 24, 48, 72 and 96-h after exposure was 79.54 ± 0.007, 52.17 ± 0.006, 30.62 ± 0.008 and 11.34 ± 0.016 mg/l respectively. Conclusions: Analysis related to the characterization of the properties of silver nanoparticles proves bioreduction of silver ions by sargassum seaweed extract. According to the results the mortality rates of common carp showed an increasing trend with increasing concentration and exposure time, which indicates the toxicity of this substance in high concentration for common carp.

BACKGROUND: Oxidative stress is believed to be one of the major causes of tissue damage in aquatic animals exposed to heavy metals. It leads to certain changes in the antioxidant and enzyme system. Given the fact that research on the effect of sub-acute toxicity of silver nitrate in shrimps is not very developed, the present study can be conducive to formulating the international standards of contamination of shrimps with silver nitrate.OBJECTIVES: The present study aimed to evaluate the toxic effects of silver nitrate on the changes in the antioxidant and enzyme systems of hepatopancreas, muscle and gills of Litopenaeus vannamei.METHODS: After acclimatization of shrimps, they were exposed to silver nitrate with concentrations of 0.0084, 0.021, 0.042 and 0.063 mg/L for 21 days. At the end of the experimental period, gill, muscle and hepatopancreas were sampled, and the changes in the antioxidant system (SOD, GPx and GST) and metabolic enzymes (ALT, ALP, AST and LDH) were examined.RESULTS: There was no significant difference in terms of SOD and GST activity in the gill and muscle of the exposed shrimps (P>0.05). However, GPx in treatment 4 increased significantly in gill and muscle while it saw a decrease in hepatopancreas (P<0.05). In hepatopancreas, GST significantly increased in treatments 3 and 4 (P<0.05) whereas SOD did not show any significant changes compared with other treatments (P>0.05). The metabolic enzymes of the muscle did not show any significant differences in any of the treatments (P>0.05), but in gill, the level of ALT in treatment 4 decreased significantly while the levels of AST and LDH in treatment 3 and 4 significantly increased (P<0.05). In hepatopancreas, the activity of ALT in treatments 2 and 4, AST in treatments 3 and 4, and ALP in all treatment except treatment 1 saw significant reduction. Nevertheless, LDH in treatments 3 and 4 had a significant rise (P<0.05).CONCLUSIONS: A significant increase in GST and LDH as well as a significant decrease in GPx and ALT, AST and ALP enzymes in the hepatopancreas revealed that the antioxidant and enzyme system of shrimps is further disturbed with the rise in silver nitrate concentration in the hepatopancreas compared to the gill and muscle.

BACKGROUND:  Considering the progressing tendency of administration of nanomaterials products in the world and their entrance to aquatic ecosystems, their toxicity assessment on the aquatic environment and proposing the biocompatible solutions in their production seems indispensable. OBJECTIVES: In this study, the toxicity of silver nanoparticles (AgNPs), chemical and biosynthetic forms were evaluated using the biomarker, artemia nauplii (Artemia fransiscana). METHODS: For toxicity assessment, the OECD standard method was used. The artemia nauplii were exposed to additive serial concentration of biosynthetic and chemical silver nanoparticles. For biosynthesis of silver nanoparticles, aqueous extracts of two species of marine macroalgae Ulva flexuosa (green algae) and Sargassum boveanum (brown algae) were used. Artemia nauplii mortality in the times of 12, 24, 36 and 48 hours after exposure to silver nanoparticles were recorded and analyzed via Probit software. RESULTS: Survey findings showed that not only the toxicity of these three types of silver nanoparticles on artemia nauplii increased in a dose- dependent manner, but also their toxicity increased along with duration of exposure time. The toxicity of these nanoparticles were significantly different (P<0.05). The 48 h LC50 value of chemical AgNPs in the artemia nauplii was 31.8 mg/l, while 48 h LC50 for biosynthesis AgNPs  produced by U. flexuosa, and S. boveanum were 366.96 and 141.16 mg/l respectively. CONCLUSIONS: Comparison of the toxicity of these three types of AgNPs on artemia nauplii showed that, the chemical form of AgNPs was more toxic (up to 10 times) than a biosynthetic form of AgNPs. Moreover, the source of biosynthesis of silver nanoparticles had a considerable impact on toxicity of final production, because a biosynthetic form of AgNPs produced by U. flexuosa was less toxic than the same form prepared from S. boveanum.