Biosilica-nanogold composite: Easy-to-prepare catalyst for soman degradation

A very fast single-step biosynthesis of gold nanoparticles (AuNPs) using algal cells of Mallomonas kalinae (MK) is introduced. The average particle size of crystalline AuNPs was approximately 10 nm. Subsequently, the catalytic activity of two systems - MK-biosilica scales and MK-biosilica scales with AuNPs - was compared with a control hydrolysis of soman (GD) performed in demineralized water. The kinetics of GD degradation was studied using a gas chromatography with mass detector (GC-MS) and solid-phase microextraction. The residual content of GD was 3.8% and 3.5% for both initial concentrations of GD (68 mu g mL(-1) and 340 mu g L-1, respectively) after 48 h of testing when nanogold was used as a catalyst. Experimental results confirmed the catalytic activity of biosynthesized AuNPs, as well as the role of biosilica itself in the degradation of GD.Web of Science12227126

Diversity of allochtonous substances detected in bee pollen pellets

Received: 2016-08-07 | Accepted: 2016-09-13 | Available online: 2017-09-30http://dx.doi.org/10.15414/afz.2017.20.03.60-65This paper quantifies the diversity of natural and artificial allochthonous materials in bee pollen pellets and assesses their impact on potential applications. Bee products used in medicine, pharmacology and food products contain honey bee wax, propolis and flower pollens, and bee pollen pellet composition is dependent on the flower’s locality and methods used in technological preparation and storage. The quality of commercially available pollen and its positive and negative mode-of-actions are significantly influenced by natural and artificial allochthonous substances. The flower pollen pellets for this study were obtained from the Levice district in the Slovak Republic and analysed by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). These visual and chemical analyses confirmed; (i) 4 different botanical pollen species were present in the pellets, (ii) minimal harmful substances were detected; with bee fragments and dead fungal hyphae biomass noted, (iii) different types of soil particles/aggregates were adsorbed; mainly Fe, Si oxides, silicates and alumosilicates and (iv) analysis revealed one artificial Ti-Mn-Fe grain, but this was most likely a residue from technological processes. Determination of all hazardous substances is necessary for bee pollen to be widely commercially available as food nutritional and energy supplements, and this can be achieved by microscopic study and the wide range of current analytical techniques.Keywords: bee pollen, food sources, pollen pellets, soil particles, artificial contaminantsReferencesAlmeida-Muradian, L.B. et al. (2005) Chemical composition and botanical evaluation of dried bee pollen pellets. In Journal of Food Composition and Analysis, vol. 18, pp. 105−111.Campos, M.G.R. et al. (2008) Pollen composition and standardisation of analytical methods. In Journal of Apicultural Research, vol. 47, no. 2, pp. 154−161.Chauzat, M.P. et al. (2006) A Survey of Pesticide Residues in Pollen Loads Collected by Honey Bees in France. In Journal of Economic Entomology, vol. 99, no. 2, pp. 253−262.ČURLÍK, J. (2011) Potentially toxic microelements and their distribution in soils of Slovakia. Bratislava: Suma print (in Slovak).de Oliveira, R. C. et al. (2016) Bee pollen as a bioindicator of environmental pesticide contamination. In Chemosphere, vol. 163, pp. 525−534.Estevinho, L.M. et al. (2012) Portuguese bee pollen: Palynological study, nutritional and microbiological evaluation. In International Journal of Food Science and Technology, vol. 47, pp. 429−435.Futák, J. (1984) Phytogeographical division of Slovakia. In Flóra Slovenska IV/1. Bratislava: Veda, pp. 418−419 (in Slovak).Hooda, P.S. et al. (2004) The potential impact of soil ingestion on human mineral nutrition. In Science of The Total Environment, vol. 333, pp. 75−87.Kačániová, M. et al. (2004) Microflora of the honeybee gastrointestinal tract. In Folia Microbiologica, vol., 49, no. 2, pp. 169−171.Kačániová, M. et al. (2011) Mycobiota and mycotoxins in bee pollen collected from different areas of Slovakia. In Journal of Environmental Science and Health - Part B Pesticides, Food Contaminants, and Agricultural Wastes, vol. 46, pp. 623−629.Kim, H., Suh, D.W. and Kim, N.J. (2013) Fe-Al-Mn-C lightweight structural alloys: A review on the microstructures and mechanical properties. In Science and Technology of Advanced Materials, vol. 14, pp. 1−12.Klimko, M., Kluza, M. and Kreft, A. (2000) Morphology of pollen grains in three varieties of Helianthus annuus L. In Roczniki Akademii Rolniczej w Poznaniu CCCXXII Botanika, vol. 3, pp. 135−142.Knox, R.B. et al. (1997) Major grass pollen allergen Lol p 1 binds to diesel axhaust particles: Implications for asthma and air pollution. In Clinical and Experimental Allergy, vol. 27, pp. 246−251.Konvičková, Z. et al. (2016) Antimicrobial bionanocomposite–from precursors to the functional material in one simple step. In Journal of nanoparticle research, vol. 18, pp. 368.Kořenková, L. et al. (2017) Physiological response of culture media-grown barley (Hordeum vulgare L.) to titanium oxide nanoparticles. In Acta Agriculturae Scandinavica Section B: Soil and Plant Science, vol. 67, pp. 285−291.Lin, H., Gomez, I. and Meredith, J.C. (2013) Pollenkitt wetting mechanism enables species-specific tunable pollen adhesion. In Langmuir, vol. 29, pp. 3012−3023.Linskens, H.F. and Jorde, W. (1997) Pollen as food and medicine - A review. In Economic Botany, vol. 51, no. 1, pp. 78−86.Mărgăoan, R. et al. (2010) Bee collected pollen–General aspects and chemical composition. In Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca. Animal Science and Biotechnologies, vol. 67, no. (1-2), pp. 254 −259.Miklós, L. et al. (2002) Landscape atlas of the Slovak Republic. Bratislava: Ministerstvo životného prostredia SR.Nogueira, C. et al. (2012) Commercial bee pollen with different geographical origins: A comprehensive approach. In International Journal of Molecular Sciences, vol. 13, pp. 11173−11187.Ormstad, H., Johansen, B.V. and Gaarder, P.I. (1998) Airborne house dust particles and diesel exhaust particles as allergen carriers. In Clinical and Experimental Allergy, vol. 28, pp. 702−708.Punt, W. et al. (2007) Glossary of pollen and spore terminology. In Review of Palaeobotany and Palynology, vol. 143, pp. 1−81.Ruby, M.V. et al. (1999) Advances in evaluating the oral bioavailability of inorganics in soil for use in human health risk assessment. In Environmental Science and Technology, vol. 33, pp. 3697−3705.Schulte, F. et al. (2008) Chemical characterization and classification of pollen. In Analytical Chemistry, vol. 80, pp. 9551−9556.Schulz, S. et al. (2000) Composition of lipids from sunflower pollen (Helianthus annuus). In Phytochemistry, vol. 54, pp. 325−336.ŠTRBA, P. and KOSÁR, G. (2012) Diversity of vascular plants in agricultural landscape of central part of Žitný ostrov region. In Biodiversity in agricultural landscape and ecosystem. International conference of the project REVERSE-INTERREG IVC. Piešťany: 13th of June 2012. Piešťany: Centre of Plant Production Piešťany, pp. 13−16 (in Slovak).Villanueva, M.T.O. et al. (2002) The importance of bee-collected pollen in the diet: A study of its composition. In International Journal of Food Sciences and Nutrition, vol. 53, pp. 217−224

Fungus Aspergillus niger processes exogenous zinc nanoparticles into a biogenic oxalate mineral

Zinc oxide nanoparticles (ZnO NPs) belong to the most widely used nanoparticles in both commercial products and industrial applications. Hence, they are frequently released into the environment. Soil fungi can affect the mobilization of zinc from ZnO NPs in soils, and thus they can heavily influence the mobility and bioavailability of zinc there. Therefore, ubiquitous soil fungus Aspergillus niger was selected as a test organism to evaluate the fungal interaction with ZnO NPs. As anticipated, the A. niger strain significantly affected the stability of particulate forms of ZnO due to the acidification of its environment. The influence of ZnO NPs on fungus was compared to the aqueous Zn cations and to bulk ZnO as well. Bulk ZnO had the least effect on fungal growth, while the response of A. niger to ZnO NPs was comparable with ionic zinc. Our results have shown that soil fungus can efficiently bioaccumulate Zn that was bioextracted from ZnO. Furthermore, it influences Zn bioavailability to plants by ZnO NPs transformation to stable biogenic minerals. Hence, a newly formed biogenic mineral phase of zinc oxalate was identified after the experiment with A. niger strain's extracellular metabolites highlighting the fungal significance in zinc biogeochemistry.Web of Science64art. no. 21

Mycosynthesis of metal-containing nanoparticles - Synthesis by ascomycetes and basidiomycetes and their application

Fungi contain species with a plethora of ways of adapting to life in nature. Consequently, they produce large amounts of diverse biomolecules that can be generated on a large scale and in an affordable manner. This makes fungi an attractive alternative for many biotechnological processes. Ascomycetes and basidiomycetes are the most commonly used fungi for synthesis of metal-containing nanoparticles (NPs). The advantages of NPs created by fungi include the use of non-toxic fungus-produced biochemicals, energy efficiency, ambient temperature, pressure conditions, and the ability to control and tune the crystallinity, shape, and size of the NPs. Furthermore, the presence of biomolecules might serve a dual function as agents in NP formation and also capping that can tailor the (bio)activity of subsequent NPs. This review summarizes and reviews the synthesis of different metal, metal oxide, metal sulfide, and other metal-based NPs mediated by reactive media derived from various species. The phyla ascomycetes and basidiomycetes are presented separately. Moreover, the practical application of NP mycosynthesis, particularly in the fields of biomedicine, catalysis, biosensing, mosquito control, and precision agriculture as nanofertilizers and nanopesticides, has been studied so far. Finally, an outlook is provided, and future recommendations are proposed with an emphasis on the areas where mycosynthesized NPs have greater potential than NPs synthesized using physicochemical approaches. A deeper investigation of the mechanisms of NP formation in fungi-based media is needed, as is a focus on the transfer of NP mycosynthesis from the laboratory to large-scale production and application.Web of Science241art. no. 30

Mycosynthesis of metal-containing nanoparticles-fungal metal resistance and mechanisms of synthesis

In the 21st century, nanomaterials play an increasingly important role in our lives with applications in many sectors, including agriculture, biomedicine, and biosensors. Over the last two decades, extensive research has been conducted to find ways to synthesise nanoparticles (NPs) via mediation with fungi or fungal extracts. Mycosynthesis can potentially be an energy-efficient, highly adjustable, environmentally benign alternative to conventional physico-chemical procedures. This review investigates the role of metal toxicity in fungi on cell growth and biochemical levels, and how their strategies of resistance, i.e., metal chelation, biomineral formation, biosorption, bioaccumulation, compartmentalisation, and efflux of metals from cells, contribute to the synthesis of metal-containing NPs used in different applications, e.g., biomedical, antimicrobial, catalytic, biosensing, and precision agriculture. The role of different synthesis conditions, including that of fungal biomolecules serving as nucleation centres or templates for NP synthesis, reducing agents, or capping agents in the synthesis process, is also discussed. The authors believe that future studies need to focus on the mechanism of NP synthesis, as well as on the influence of such conditions as pH, temperature, biomass, the concentration of the precursors, and volume of the fungal extracts on the efficiency of the mycosynthesis of NPs.Web of Science2322art. no. 1408

Colloidal stability of phytosynthesised gold nanoparticles and their catalytic effects for nerve agent degradation

Herein, Tilia sp. bract leachate was used as the reducing agent for Au nanoparticles (Au NPs) phytosynthesis. The colloidal properties of the prepared Au NPs were determined to confirm their stability over time, and the NPs were then used as active catalysts in soman nerve agent degradation. The Au NPs characterisation, reproducibility and stability studies were performed under transmission electron microscopy, ultraviolet visible spectroscopy and with zeta -potential measurements. The reaction kinetics was detected by gas chromatography coupled with mass spectrometry detector and solid-phase micro-extraction to confirm the Au NPs applicability in soman hydrolysis. The 'green' phytosynthetic formation of colloidal crystalline Au NPs with dominant quasi-spherical shape and 55 +/- 10 nm diameter was successfully achieved, and there were no significant differences in morphology, zeta -potential or absorbance values observed during the 5-week period. This verified the prepared colloids' long-term stability. The soman nerve agent was degraded to non-toxic substances within 24 h, with 0.2156 h(-1) reaction rate constant. These results confirmed bio-nanotechnology's great potential in preparation of stable and functional nanocatalysts for degradation of hazardous substances, including chemical warfare agents.Web of Science111art. no. 407

Field application of ZnO and TiO2 nanoparticles on agricultural plants

Engineered nanoparticles (ENPs) have potential application in precision farming and sustainable agriculture. Studies have shown that ENPs enhance the efficiency of the delivery of agrochemicals and thus, have the potential to positively affect the environment, thereby improving the growth and health of the crops. However, the majority of the research on the effects of ENPs on plants and in agricultural applications have been limited to controlled laboratory conditions. These conditions do not fully consider various aspects inherent to the growth of agricultural plants in fields under changing weather and climate. Some of the most investigated ENPs in the agricultural research area are ZnO nanoparticles (ZnO NPs) and TiO2 nanoparticles (TiO2 NPs). ZnO NPs have the potential to increase crop production and stress resistance, mainly by the slow release of Zn ions to crops. Unlike ZnO NPs, TiO2 NPs have less well-understood means of action, and are generally considered as plant growth promoter. This mini review presents information compiled for ZnO and TiO2 NPs(,) their influence on agricultural plants with emphasis on particularly effect on plant growth, nutrient distribution and pollution remediation under field conditions. It is concluded that in order to gain a broader perspective, more field studies are needed, particularly multigeneration studies, to fully understand the effects of the ENPs on agricultural plants' growth and improvement of their health.Web of Science1111art. no. 228

Effect of Carbonates and Bivalent Cations and Their Relationships with Soil Organic Matter from the View Point of Aggregate Formation

The effect of carbonates on soil structure has not been sufficiently studied yet, despite the fact that in the literature their positive impact is mentioned mostly. Carbonates are the source of bivalent cations in soil solution and may be involved in stabilization of the aggregates, because negatively charged organic materials can be adsorbed onto the surface of clay by bivalent or polyvalent cations. We studied the effect of carbonates and bivalent cations and their relationships with soil organic matter (SOM) from the point of view of aggregate formation. The studies were carried out in several fields located on loamy Calcaric Chernozem, loamy Haplic and Mollic Fluvisols. The results showed that between exchangeable Mg2+ and water-stable macro-aggregates (WSAma) in size fractions >2 mm, positive correlations were found; however, the content of Mg2+ negative correlated with the contents of WSAma in 2 mm; however, between SBC as well as CEC and smaller size fractions of WSAma >1 mm and WSAmi negative correlations were observed. Statistically significant negative correlations were observed between SOM content in WSA and carbonate content, and this effect was stronger in relation to the labile carbon. There were also positive correlations between SOM in WSA and SBC and CEC found if all loamy soils were assessed together

Unexpected formation of Ag2SO4 microparticles from Ag2S nanoparticles synthesised using poplar leaf extract

There are several methods for inorganic nanoparticle synthesis. However, these methods usually need high energy and generate toxic waste. Therefore, we explored biocrystallisation as a cheaper and safer method. We used poplar leaf extract to produce silver-based nanoparticles. Here, we studied nanoparticle crystallisation under various conditions such as light–dark cycles. Silver nanoparticles were analysed by transmission electron microscopy for particle morphology and size distribution, selected area electron diffraction for crystal structure and energy-dispersive X-ray for elemental analysis. Results show that individual Ag2S acanthite nanoparticles are formed after 3 days of dynamic cultivation in the dark. These particles have a typical spherical shape, which is found also in the form of aggregates with vermicular structure. These particles were unexpectedly transformed into Ag2SO4 micro-sized particles of good dispersity and high crystallinity upon application of light–dark cycles. Overall, our finding shows that poplar leaf extract is a good medium to catalyse the formation of silver-based nanoparticles.Web of Science12455655

Heterotrophic leaching and its application in biohydrometallurgy

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