The effects of dietary exposure to Magnéli phase titanium suboxide and titanium dioxide on rainbow trout (Oncorhynchus mykiss).

Magnéli phase titanium suboxides (Magnéli TiOx) are promising, novel materials with superior properties compared to TiO2, they are substoichiometric titanium oxides with the chemical formula TinO2n-1 (where n ≥ 1). In this study, for the first time, subchronic effects of dietary intake of Magnéli TiOx were evaluated and compared with TiO2 particles of similar size, in concentrations 0.1% and 0.01% of feed. The experiment consisted of 38 d of an exposition period and 14 d of a depuration period. Minor effects on plasma biochemical profile and morphological parameters were recorded. A reduced count of leukocytes was found in the blood of both Magnéli TiOx and TiO2 exposed fish, suggesting immunotoxic effects. Erythrocytosis was specific for Magnéli TiOx. Indices of oxidative stress, namely increased lipid peroxidation in liver, increased activity of superoxide dismutase in liver, kidney and gills and glutathione S-transferase (GST) in gills, as well as decreased activity of ceruloplasmin and GST in liver were found predominantly in fish exposed to TiO2. Histopathological examination revealed increased lipid-like vacuolation in the liver, the presence of hyaline droplets in renal tubules and multiplication of mucous glands in the epidermis in both tested substances and intestine damage in TiO2 groups. Overall, in Magnéli TiOx exposed groups, fewer adverse effects compared to TiO2 expositions were recorded. Their wider practical implementation in place of TiO2 is therefore beneficial.

Effect of Gold Nanoparticles and Ions Exposure on the Aquatic Organisms.

An increase in the production and usage of gold nanoparticles (AuNPs) triggers the necessity to focus on their impact on ecosystems. Therefore, the purpose of this study was to investigate the acute toxicity of AuNPs and ionic gold (Au (III)) to organisms representing all trophic levels of the aquatic ecosystem, namely producers (duckweed Lemna minor), consumers (crustacean Daphnia magna, embryos of Danio rerio) and decomposers (bacteria Vibrio fischeri). The organisms were exposed according to a standardized protocol for each species and endpoints. The AuNPs (1.16 and 11.6 d.nm) were synthesized using citrate (CIT) and polyvinylpyrrolidone (PVP) as capping agents, respectively. It was found, that Au (III) was significantly more toxic than AuNPs PVP and AuNPs CIT. AuNPs showed significant toxicity only at high concentrations (mg/L), which are not environmentally relevant in the present time, but a cautious approach is advised, due to the possibility of interactions with other contaminants.

The effect of silver nanoparticles and silver ions on zebrafish embryos (Danio rerio).

OBJECTIVES: The aim of this study was to establish and evaluate the mortality rate, hatching rate and observe the presence of sublethal changes in zebrafish embryos after exposure to silver ions and nanoparticles. METHODS: Tests were conducted on newly fertilized zebrafish embryos, according to the modified OECD guideline 236, using a semistatic method and 96 hour incubation time. Silver nitrate and two different silver nanoparticles, stabilized with 0.01% solution of maltose and gelatine in the first case, and stabilized with polyvinylpyrrolidone, in the latter, were tested. RESULTS: Significant differences in toxicity of tested substances were recorded. The value of 96hLC50 for silver nitrate was 58.44 µg/L. The value of 96hLC50, calculated for silver nanoparticles stabilized with 0.01% solution of maltose and gelatine, was nearly 100 times higher, 4.31 mg/L. The value 96hLC50 for silver nanoparticles stabilized with polyvinylpyrrolidone exceeded 100mg/L, occurrence of sublethal effects caused by silver nanoparticles stabilized with polyvinylpyrrolidone was insignificant in most of the exposition groups, but only in this substance caused decreased hatching rate. CONCLUSION: Properties of different silver nanoparticles play an important role in levels of their toxicity and predominant mechanisms of action. In general, silver nanoparticles are less toxic for Danio rerio embryos than silver ions.