Traditional supplements of selenium generally have a low degree of absorption and increased toxicity. Therefore, it is imperative to develop innovative systems as transporters of selenium compounds, which would raise the bioavailability of this element and allow its controlled release in the organism. Nanoscale selenium has attracted a great interest as a food additive especially in individuals with selenium deficiency, but also as a therapeutic agent without significant side effects in medicine. This review is focused on the incorporation of nanotechnological applications, in particular exploring the possibilities of a more effective way of administration, especially in selenium-deficient organisms. In addition, this review summarizes the survey of knowledge on selenium nanoparticles, their biological effects in the organism, advantages, absorption mechanisms, and nanotechnological applications for peroral administration.

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Nano-selenium and its nanomedicine applications: a critical review.

Selenium nanoparticles (SeNPs) are gaining importance in the field of medicine owing to their antibacterial and anticancer properties. SeNPs are biocompatible and non-toxic compared to the counterparts, selenite (SeO3 (-2)) and selenate (SeO4 (-2)). They can be synthesized by physical, chemical, and biological methods and have distinct bright orange-red color. Biogenic SeNPs are stable and do not aggregate owing to natural coating of the biomolecules. Various hypotheses have been proposed to describe the mechanism of microbial synthesis of SeNPs. It is primarily a two-step reduction process from SeO4 (-2) to SeO3 (-2) to insoluble elemental selenium (Se(0)) catalyzed by selenate and selenite reductases. Phenazine-1-carboxylic acid and glutathione are involved in selenite reduction. Se factor A (SefA) and metalloid reductase Rar A present on the surface of SeNPs confer stability to the nanoparticles. SeNPs act as potent chemopreventive and chemotherapeutic agents. Conjugation with antibiotics enhances their anticancer efficacy. These also have applications in nanobiosensors and environmental remediation.

Biogenic selenium nanoparticles: current status and future prospects

Selenium nanoparticles as a nutritional supplement

Selenium (Se) is an essential element for humans and animals, which occurs ubiquitously in the environment. It is present in trace amounts in both organic and inorganic forms in marine and freshwater systems, soils, biomass and in the atmosphere. Low Se levels in certain terrestrial environments have resulted in Se deficiency in humans, while elevated Se levels in waters and soils can be toxic and result in the death of aquatic wildlife and other animals. Human dietary Se intake is largely governed by Se concentrations in plants, which are controlled by root uptake of Se as a function of soil Se concentrations, speciation and bioavailability. In addition, plants and microorganisms can biomethylate Se, which can result in a loss of Se to the atmosphere. The mobilization of Se across soil-plant-atmosphere interfaces is thus of crucial importance for human Se status. This review gives an overview of current knowledge on Se cycling with a specific focus on soil-plant-atmosphere interfaces. Sources, speciation and mobility of Se in soils and plants will be discussed as well as Se hyperaccumulation by plants, biofortification and biomethylation. Future research on Se cycling in the environment is essential to minimize the adverse health effects associated with unsafe environmental Se levels.

Selenium Cycling Across Soil-Plant-Atmosphere Interfaces: A Critical Review

Nanoparticles applied to plant science: a review.

Selenium is well known as an essential trace element since the 20th century, but it can be overdosed easily because of its toxicity. According to the present regulations [1] only the potentially most harmful, inorganic selenium salts can be added to any comestibles. Elemental selenium is considered as the least toxical of all selenium forms and in the same time supplementation with its nano-size particles has the same or better bioavailability compared to its salts. In our experiments we managed to produce nano-size (100-500nm) elemental selenium by using probiotic yogurt bacteria in a fermentation procedure. We developed the laboratory technology of product purification and recovery from bacteria.

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Elemental, Nano-Sized (100-500 nm) Selenium Production by Probiotic Lactic Acid Bacteria

The uptake, accumulation and biological effects of red nano-sized elemental selenium (nanoSe) in comparison to selenate were investigated in plant system at the first time. The data clearly indicated that red nanoSe was taken up by tobacco callus cultures and rooted tobacco plantlets. The roots of regenerated plantlets accumulated selenium in very high concentrations, 2,947 ± 99 mg/kg DW, from the medium containing 530 μM nanoSe. The biological effects of nanoSe were different from the selenate ion in plant tissue culture. NanoSe (265–530 μM concentration range) stimulated the organogenesis and the growth of root system significantly (~40 %) while selenate did not show these effects at any concentration moreover inhibited both callus growth and root regeneration totally in 265–530 μM concentrations.

Accumulation of Red Elemental Selenium Nanoparticles and Their Biological Effects in Nicotinia Tabacum

Salt marsh soils sequester large amounts of organic matter (OM). The question we address in this study is how OM quality changes during initial soil development in salt marshes. To answer this question, we studied soils at six sites at the German North Sea coast. At each site, three zones – low, mid, and high marsh – that differ in inundation frequency were analyzed. We found that organic carbon (OC) and nitrogen (N) contents increased significantly with decreasing inundation frequency at all sites, while inorganic carbon contents decreased. δ13C signatures of the OC strongly decreased at all sites from low to high marsh (from − 15.3 to − 21.5‰), indicating a decrease in the proportion of marine-derived OC. The decrease in sea-derived OC was associated with an increase in C/N ratio, which can be attributed to the difference in the C/N ratios between sea- and land-derived OM inputs. Increases in OC and N contents in the bulk soils during soil development resulted from increases of the OC content in the coarse size fraction (> 200 μm), and were associated with increases in the content of hot water extractable C and N (Chwe and Nhwe). The proportion of OM found in the fraction

Changes in soil organic matter quality during sea-influenced marsh soil development at the North Sea coast

As an essential trace element selenium plays a significant role in many physiological functions of the organs. It is found within muscles as selenocystein in selenoprotein N, which is involved in redox-modulated calcium homeostasis and in protection against oxidative stress. The effects of two different selenium compounds (selenate and NanoSe in 0.5 and 5 ppm concentration for two weeks) on muscle properties of mice were examined by measuring in vivo muscle performance, in vitro force in soleus (SOL) and extensor digitorum longus (EDL) muscles and changes in intracellular Ca2+ concentration in single fibers from flexor digitorum brevis (FDB) muscle.. Western-blot analysis on muscle lysates of EDL and SOL were used to measure the selenoprotein N expression. Control mice received 0.3 ppm Se. While the grip force did not change, 5 ppm selenium diets significantly increased the speed of voluntary running and the daily distance covered. Both forms of selenium increased significantly the amplitude of single twitches in EDL and SOL muscle in a concentration dependent manner. Selenate increased fatigue resistance in SOL. The amplitude of the calcium transients evoked by KCl depolarization increased significantly from the control of 343 ± 44 nM to 671 ± 51 nM in the presence of 0.5 ppm selenate in FDB fibers. In parallel, the rate of calcium release during short depolarizations increased significantly from 28.4 ± 2.2 to 45.5 ± 3.8 and 52.1 ± 1.9 μM/ms in the presence of 0.5 ppm NanoSe and selenate, respectively. In 0.5 ppm concentration both selenium compounds increased significantly the selenoprotein N expression only in EDL muscle. Selenium supplementation augments calcium release from the sarcoplasmic reticulum thus improves skeletal muscle performance. These effects are accompanied by the increased selenoprotein N expression in the muscles which could result in increased oxidative stress tolerance in case of long lasting contraction.

https://link.springer.com/content/pdf/10.1186%2Fs12986-016-0134-6.pdf

Beáta Babka

Papers

Elemental, Nano-Sized (100-500 nm) Selenium Production by Probiotic Lactic Acid Bacteria

Accumulation of Red Elemental Selenium Nanoparticles and Their Biological Effects in Nicotinia Tabacum

Changes in soil organic matter quality during sea-influenced marsh soil development at the North Sea coast

Dietary selenium augments sarcoplasmic calcium release and mechanical performance in mice.

Clustering oxbow lakes in the Upper-Tisza Region on the basis of stable isotope measurements