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

Biosynthesis of gold nanoparticles using diatoms-silica-gold and EPS-gold bionanocomposite formation

Novel synthesis of gold nanoparticles, EPS-gold, and silica-gold bionanocomposites by biologically driven processes employing two diatom strains (Navicula atomus, Diadesmis gallica) is described. Transmission electron microscopy (TEM) and electron diffraction analysis (SAED) revealed a presence of gold nanoparticles in the experimental solutions of the diatom culture mixed with tetrachloroaureate. Nature of the gold nanoparticles was confirmed by X-ray diffraction studies. Scanning electron microscopy (SEM) and TEM showed that the nanoparticles were associated with the diatom frustules and extracellular polysaccharides (EPS) excreted by the diatom cells. Due to its accessibility, simplicity, and effectiveness, this method of nanocomposites preparation has great importance for possible future applications

Magnetically modified nanogold-biosilica composite as an effective catalyst for CO oxidation

The temperature-dependent biosynthesis of gold nanoparticles (AuNP) using diatom cells of Diadesmis gallica was successfully performed. The resulting biosynthesis product was a bio-nanocomposite containing AuNP (app. 20 nm) subsequently anchored on the silica surface of diatomaceous frustules. As-prepared nanogold-biosilica composite was tested as catalyst in the oxidation of carbon monoxide using gas chromatograph with thermal conductivity detector. For catalytic activity enhancement, bionanocomposite was magnetically modified by ferrofluid using two different methods, i.e., with and without the use of methanol. The oxidation of CO at 300 degrees C was 58-60% in the presence of nanogold-biosilica composites. CO conversion at 300 degrees C was only 15% over magnetically responsive sample modified in the presence of methanol. On the other hand, complete CO conversion was reached over direct (without methanol) magnetically modified nanogold-biosilica composite at 330 degrees C (GHSV = 60 l g(-1) h(-1)). Our results show, that the type of magnetic modification can influence the catalytic activity of bionanocomposite. The best catalytic effect in CO conversion established direct magnetically modified nanogold-biosilica composite.Web of Science1271158114

Ag-AgCl nanoparticles fixation on electrospun PVA fibres: Technological concept and progress

Polymer-metal based material with unique 3D structure is an attractive substrate for the development of biomedical applications. A novel preparation of the composite from polymer fibres and silver nanoparticles has been designed through: (1) preparation of silver nanoparticles by phytosynthesis and (2) incorporation of these nanoparticles in a fibrous membrane prepared by electrospinning. The nanoparticle biosynthesis was performed in a pure environmental-friendly, easy, static, bottom-up in vitro regime using Tilia sp. leachate. TEM and XRD depict the formation, stabilisation and encapsulation of crystalline silver (14 +/- 9 nm) nanoparticles (NPs) in one simple step with low tendency to aggregate. We achieved successful incorporation in the uniform electrospun 221 +/- 24 nm poly(vinylalcohol) fibres, and this confirms the possibility of its use in the biomedical field. Both SEM with EDX and TEM analysis determined fibre uniformity with the presence of silver NPs, and ICP-AES confirmed the relatively similar metal concentration throughout the triplicate measurement of fibre structures on the 2 x 2 cm area in the following manner: 0.303 +/- 0.018 wt. %, 0.282 +/- 0.017 wt. %, and 0.281 +/- 0.017 wt. %. Our hypothesis is based on previously verified preparation of active silver NPs and the easily prepared PVA electrospun fibres which act as a water soluble matrix. The simple methodology of incorporating biosynthetically prepared NPs in the PVA fibers highlights the effectiveness of this material, with simple release from water-soluble PVA and final activation of the prepared NPs.Web of Science9art. no. 1552

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

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

Phase transformation after heat treatment of Cr-Ni stainless steel powder for 3D printing

Today, Ni-Cr steel is used for advanced applications in the high-temperature and electrical industries, medical equipment, food industry, agriculture and is applied in food and beverage packaging and kitchenware, automotive or mesh. A study of input steel powder from various stages of the recycling process intended for 3D printing was conducted. In addition to the precise evaluation of the morphology, particle size and composition of the powders used for laser 3D printing, special testing and evaluation of the heat-treated powders were carried out. Heat treatment up to 950 degrees C in an air atmosphere revealed the properties of powders that can appear during laser sintering. The powders in the oxidizing atmosphere change the phase composition and the original FeNiCr stainless steel changes to a two-phase system of Fe3Ni and Cr2O3, as evaluated by X-ray diffraction analysis. Observation of the morphology showed the separation of the oxidic phase in the sense of a brittle shell. The inner part of the powder particle is a porous compact core. The particle size is generally reduced due to the peeling of the oxide shell. This effect can be critical to 3D printing processing, causing defects on the printed parts, as well as reducing the usability of the precursor powder and can also change the properties of the printed part.Web of Science1515art. no. 534

Biogenic silver nanoparticles: What we know and what do we need to know?

Nanobiotechnology is considered to be one of the fastest emerging fields. It is still a relatively new and exciting area of research with considerable potential for development. Among the inorganic nanomaterials, biogenically synthesized silver nanoparticles (bio-AgNPs) have been frequently used due to their unique physicochemical properties that result not only from their shape and size but also from surface coatings of natural origin. These properties determine antibacterial, antifungal, antiprotozoal, anticancer, anti-inflammatory, and many more activities of bio-AgNPs. This review provides the current state of knowledge on the methods and mechanisms of biogenic synthesis of silver nanoparticles as well as their potential applications in different fields such as medicine, food, agriculture, and industries.Web of Science1111art. no. 290

Exploring the impact of metal-based nanofertilizers: A case study on sunflower pollen morphology and yield in field conditions

On a daily basis, a wide range of materials including inorganic nanoparticles (NPs) inadvertently find their way into the environment. Meanwhile, intentionally used NPs, such as the new generation of nanofertilizers (NFs) are designed to enhance agronomic production. However, their physicochemical properties and not-so-well understood effects raise potential risks to the plant reproductive cycle, specifically pollen development, a subject largely absent in academic research. Even slight contamination, deformation, or aberration of pollen could have enormous impacts on the ecosystem. Thus, our objective was to evaluate the influence of various metal-based NPs on sunflower pollen morphology and its yield. Nano-formulations were applied during the 2019-2021 agronomic seasons on two sunflower hybrids, Neostar and Edison, in Doln & aacute; Malanta, near Nitra, Slovak Republic. Pollen morphology findings indicated that conventional ZnSO4 had the most positive impact on the size of pollen grains compared to ZnO-NPs, Fe3O4-NPs, and the NP-free control. Gold-NPs on SiO2 mesoporous silica (AuSi-NPs) showed a statistically insignificant impact, while the use of TiO2-NPs in agriculture remained a topic of debate. Surprisingly, pollen characteristics did not fully correspond to crop yields. Despite causing a reduction in pollen grain size, the TiO2-NPs consistently showed the highest yield compared to other variants. Employing low concentrations of NFs did not notably alter pollen morphology, reinforcing our commitment to eco-friendly, precise, and sustainable agriculture.Web of Science1312art. no. 292

Posouzení možností aplikace bioloužení na vybrané metalurgické odpady

Import 08/08/2006PrezenčníNeuveden