Silver nanoparticles (AgNP) are integrated into various products due to their antimicrobial characteristics and hence, the application of AgNP is increasing. During production, use and disposal AgNP are emitted and enter the environment via several pathways. Soils are considered a major sink of AgNP. The aim of the present study was to determine the toxic effect of AgNP on Folsomia candida reproduction to illustrate potential impact on terrestrial ecosystems. The AgNP-dependent reduction of F. candida reproduction was studied in RefeSol 01-A, LUFA 2.2 and OECD soil at 0.3 µg – 50 mg Ag kg-1. To simulate realistic exposure pathways, effects on F. candida reproduction after the application of AgNP via sewage sludge and after aging this treatment in the soil for up to 140 days were studied using environmentally relevant concentrations. The OECD representative AgNP, NM-300K, and AgNO3, as a metal salt reference, were used in all experiments. The generated data demonstrate that the presence of AgNP in the soil in the low mg Ag kg-1 concentration range results in significant, but concentration independent inhibition of F. candida reproduction in RefeSol 01-A and LUFA 2.2. Significant inhibition of F. candida reproduction due to AgNP was also observed for soil amended with AgNP treated sludge. An increase in inhibition with aging of the AgNP in the soil was evident. In conclusion, our results demonstrate that, at environmentally relevant concentrations, AgNP adsorption to sludge and subsequent aging in soil lead to a toxic effect on soil invertebrates.

Fucoxanthin (FX) is a carotenoid from a marine origin that has an important role in our health, especially in the regulation and alleviation of type 2 diabetes. Its specific molecular structure makes it very unstable, which greatly affects its delivery in the body. In this study, FX was encapsulated in a mono-carrier using a hydrolyzed zein to form a nanocomplex with a stable structure and chemical properties (FZNP). Its stability was demonstrated by characterization and the efficacy of FX before and after encapsulation in alleviating diabetes in mice, which was evaluated by in vivo experiments. FZNP reduced the level of fasting blood glucose and restored it to normal levels in T2DM mice, which was not caused by a decrease in food intake, and effectively reduced oxidative stress in the organism. Both FX and FZNP repaired the hepatocyte and pancreatic β-cell damage, increased serum SOD and reduced INS values significantly, upregulated PI3K-AKT genes as well as CaMK and GNAs expression in the pancreas. FZNP increased ADPN and GSH-PX values more significantly and it decreased serum HOMA-IR and MDA values, upregulated GLUT2 expression, promoted glucose transport in pancreatic and hepatocytes, regulated glucose metabolism and glycogen synthesis with much superior effects than FX.

Context: Our research contributes to the knowledge of using soil algae to combat soil degradation. Aims: We tested green algae (Klebsormidium flaccidum) and a field soil algae community in a 3-month greenhouse experiment and studied their performance on two substrates: (1) sand from the Ordos Desert; and (2) artificial desert sand (washed sand). Methods: A rapid fluorescence microscopy-Image J method was developed to estimate the abundance of algae. We studied the effects of four soil amendments (biochar, clay, organic matter, geohumus) on the development of green algae, field algae and biological soil crusts. Key results: The field algae preferred washed sand. All amendments had a positive effect on the abundance of K. flaccidum and field algae. Biological soil crusts were generally lower in control and organic matter treatments, but relatively higher in biochar and clay treatments. No relationship between algal abundance and soil crust stability was found in this short-term experiment. Conclusions: Our rapid fluorescence microscopy-Image J method quantitatively estimated algal abundance aunder different conditions, providing an indirect indicator of their growth status. Implications: This method can be used to make recommendations on soil amendments and their effect on algal growth studies.

Background: Toxicity of silver nanoparticles (AgNP) has been studied frequently due to a rise in application in various products. Various studies on AgNP toxicity with terrestrial and aquatic organisms confirmed their negative effects. In our previous experiments, strong variability was observed in the reproduction of Collembola (Folsomia candida) in different repeats. To investigate the effects of silver on the reproduction of Folsomia candida, they were exposed in laboratory-controlled conditions to AgNP and silver nitrate (AgNO₃) at a concentration of 30 mg/kg dry soil for 28 days and compared to controlled individuals not exposed to silver. We repeated reproduction tests on the toxicity of silver to Folsomia candida four times throughout one year (April, July, October and January) in order to explore the temporal variability of their outcome. Results: While adult survival was similar in all treatments and seasons, reproduction in the control increased from April to October. Significantly lower reproduction was found in January with only 385–424 juveniles per vessel, compared to 504–633 individuals in other months. Strong toxic effects of both silver treatments were observed in July, April and October. However, AgNP showed no toxic effects on the reproduction of F. candida in January. The relative toxicity of both substances varied between single experiments: AgNP were more toxic than AgNO₃ in April and July, and less toxic in October and January. Conclusion: These findings indicate that the reproduction of F. candida in the control had a significant effect on the results of the toxicology experiments. Moreover, we demonstrated the reproductive toxicity of AgNP in soil at a much lower concentration than reported thus far. Therefore, to guarantee reliability and reproducibility, we recommend to disregard any test results where the reproduction rate of F. candida in the control is significantly different from the average in the respective laboratory, even if the validity criteria of the test are met.

Oxygen optical microsensors are a sensitive method to monitor oxygen production and consumption in soils, sediments, and aquatic systems. They have been used widely to analyze the activity and metabolism of aerobic organisms, also in ecotoxicological tests. We aimed to assess the suitability of a contact-free device to measure cell respiration and photosynthesis for future applications in ecotoxicological tests. One of the most important advantages of this modified method is that respiration and photosynthesis of test organisms which are contaminated with test chemicals can be measured without contact between sensor and test medium. Therefore, it avoids sensor contamination. In an array of calibration tests with Chlorella vulgaris in green algae medium, algal cell activity was well-correlated with cell counts. Results clearly showed that, compared to O₂ evolution rate, O₂ assimilation rate measured by oxygen optical microsensors in a contact-free manner could better predict the algae cell counts. In a second test series we measured O₂ assimilation rate in soil from a field experiment inoculated with different communities of terrestrial algae. No significant difference was observed when comparing measurements of their activity with microsensors to results obtained with the Warburg respiratory manometer. However, optical microsensors are much faster and more easily applied than the traditional manometer. Therefore, the developed method appears promising for application in ecotoxicological tests in the future.

The toxicity of silver nanoparticles (AgNPs) has been intensely studied, due to their increased applications in various products. However, most studies were conducted under laboratory conditions and short periods of time. Here we focus on how AgNPs at a concentration of 30 mg kg⁻¹ soil behave under semi-field conditions in a long-term study. The effects of AgNPs (NM-300K) and AgNO₃ in three soil treatments with and without additives on microbial biomass, mesofauna and the reproduction of Folsomia candida were studied. We measured silver concentrations by atomic absorption spectrometry. After 200, 400 and 600 days, we recorded soil microbial biomass by substrate-induced respiration, extracted the colonizing mesofauna and used part of the soil for reproduction tests with F. candida. Over the time course of the entire experiment, 71.2% of the added silver was found in the sampling soils, 9.6% in the surrounding soil, and 0.3% in the drainage water. Only in the unamended soil AgNPs and AgNO₃ showed inhibitory effects that decreased over time, although more silver was retained in the amended soils. Soil mesofauna abundance was only temporarily reduced by AgNO₃ but not by AgNPs. By the end of the experiment no more negative effects on the measured microbial biomass were observed. Biochar and compost as soil amendments demonstrated excellent remediation potential for AgNPs, both for medium- and long-term experiments.