PURPOSE: Titanium dioxide nanoparticles, 25 nm in size of crystallites (TiO2 P25), are among the most produced nanomaterials worldwide. The broad use of TiO2 P25 in material science has implied a request to evaluate their biological effects, especially in the lungs. Hence, the pulmonary A549 cell line has been used to estimate the effects of TiO2 P25. However, the reports have provided dissimilar results on caused toxicity. Surprisingly, the physicochemical factors influencing TiO2 P25 action in biological models have not been evaluated in most reports. Thus, the objective of the present study is to characterize the preparation of TiO2 P25 for biological testing in A549 cells and to evaluate their biological effects. METHODS: We determined the size and crystallinity of TiO2 P25. We used four techniques for TiO2 P25 dispersion. We estimated the colloid stability of TiO2 P25 in distilled water, isotonic NaCl solution, and cell culture medium. We applied the optimal dispersion conditions for testing the biological effects of TiO2 P25 (0-100 µg.mL-1) in A549 cells using biochemical assays (dehydrogenase activity, glutathione levels) and microscopy. RESULTS: We found that the use of fetal bovine serum in culture medium is essential to maintain sufficient colloid stability of dispersed TiO2 P25. Under these conditions, TiO2 P25 were unable to induce a significant impairment of A549 cells according to the results of biochemical and microscopy evaluations. When the defined parameters for the use of TiO2 P25 in A549 cells were met, similar results on the biological effects of TiO2 P25 were obtained in two independent cell laboratories. CONCLUSION: We optimized the experimental conditions of TiO2 P25 preparation for toxicity testing in A549 cells. The results presented here on TiO2 P25-induced cellular effects are reproducible. Therefore, our results can be helpful for other researchers using TiO2 P25 as a reference material.

• Keywords
• A549 cells, P25, dispersion, nanoparticles, nanotoxicity, titanium dioxide,
• MeSH
• A549 Cells MeSH
• Sodium Chloride MeSH
• Glutathione MeSH
• Metal Nanoparticles MeSH
• Humans MeSH
• Nanoparticles * chemistry   MeSH
• Oxidoreductases MeSH
• Lung MeSH
• Serum Albumin, Bovine * MeSH
• Titanium MeSH
• Water MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Sodium Chloride MeSH
• Glutathione MeSH
• Oxidoreductases MeSH
• Serum Albumin, Bovine * MeSH
• Titanium MeSH
• titanium dioxide MeSH Browser
• Water MeSH

Acute toxicity of zinc oxide nanoparticle (ZnO-NP, mean particle size diameter of 10 nm) powder and water-soluble salt of zinc (ZnCl2) to annelid Enchytraeus crypticus was tested using an agar-based nutrient-enriched medium with the addition of kaolin and humic acids (HA). Adults of the E. crypticus were cultivated in pure agar and in three types of modified exposure media containing different proportions of model soil constituents. Potworms were exposed to zinc in both forms (1-1000 mg kg-1 of agar) for 96 h. In experiments with ZnCl2, toxicity of zinc was the highest in pure agar followed by agar with HA and agar with kaolin and HA and the lowest toxicity was observed in agar with kaolin. The corresponding LC50 values were 13.2, 28.8, 39.4, and 75.4 mg kg-1 respectively. In contrast, zinc in the form of ZnO-NPs was most toxic in the presence of HA followed by pure agar, agar with kaolin, and kaolin with HA. In this case, LC50 values were 15.8, 43.5, 111, and 122 mg kg-1 respectively. Scanning electron microscopy revealed that the smallest agglomerates occurred in the presence of kaolin, where ZnO-NPs were sealed in a kaolin shell. This effect reduced the bioavailability and toxicity of the NPs. In contrast, larger agglomerates were observed in the presence of HA but a larger amount of zinc was dispersed in the volume of agar.

• Keywords
• Agar-based cultivation media, Humic acids, Interactions, Kaolin, Nanoparticles, Physicochemical characteristics, Worms,
• MeSH
• Agar analysis   MeSH
• Chlorides toxicity   MeSH
• Metal Nanoparticles toxicity   MeSH
• Culture Media analysis   MeSH
• Soil Pollutants toxicity   MeSH
• Oligochaeta drug effects   growth & development   MeSH
• Zinc Oxide toxicity   MeSH
• Zinc Compounds toxicity   MeSH
• Toxicity Tests, Acute methods   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Agar MeSH
• Chlorides MeSH
• Culture Media MeSH
• Soil Pollutants MeSH
• Zinc Oxide MeSH
• Zinc Compounds MeSH
• zinc chloride MeSH Browser

The effects of plant-bound zinc (Zn) and cadmium (Cd) on element uptake and their interactions in a parasite-host system were investigated in a model experiment. Male Wistar rats were divided into four groups (C, P, TC and TP). Groups TC and TP were infected with the rat tapeworm Hymenolepis diminuta. Groups C and TC were fed a standard rodent mixture (ST-1) and received 10.5 mg of Zn per week, while groups P and TP were fed a mixture supplemented with the Zn- and Cd-hyperaccumulating plant Arabidopsis halleri at a dosage of 236 mg Zn/week and 3.0 mg Cd/week. Rats were euthanized after 6 weeks, and Cd and Zn levels were determined in rat and tapeworm tissue. The results indicate that tapeworm presence did have an effect on Cd and Zn concentrations in the host tissue; the majority of tissues in infected rats had statistically significant lower Zn and Cd concentrations than did uninfected rats. Tapeworms accumulated more zinc and cadmium than did the majority of host tissues. This important finding confirms the ability of tapeworms to accumulate certain elements (heavy metals) from the host body to their own body tissues. Thus, tapeworms can decrease heavy metal concentrations in host tissues.

• Keywords
• Accumulate, Cadmium, Plant, Rat, Tapeworm, Zinc,
• MeSH
• Arabidopsis chemistry   drug effects   MeSH
• Diet MeSH
• Hymenolepis diminuta physiology   MeSH
• Cadmium metabolism   pharmacology   MeSH
• Rats MeSH
• Rats, Wistar MeSH
• Metals, Heavy metabolism   pharmacology   MeSH
• Zinc metabolism   pharmacology   MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Male MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Cadmium MeSH
• Metals, Heavy MeSH
• Zinc MeSH