Elemental Selenium Research Articles

Arylhydrazine salt‐selenium: A novel and efficient reagent system for arylselenenylation of unprotected uracil and its derivatives

AbstractA convenient and efficient reagent system of arylhydrazine salt‐selenium was developed to directly selenizing uracil preparation of 5‐selenium uracil. In the presence of this reagent, a variety of uracil/pyrimidine converts to their corresponding 5‐arylselanyluracils/5‐selenopyrimidine with good yield and high regioselectivity. Elemental selenium of commercially accessible, stable, affordable, and easy to use was used as the selenization reagent. This reaction is attractive and practical since there are no catalysts or ligands needed, and a wide range of functional groups can be tolerated.

In-situ generated elemental selenium nanograins cooperated with NiSe2 microspheres for significantly enhanced magnesium-storage performance

Rechargeable magnesium batteries (RMBs) are advantageous for large-scale energy storage applications, but their development is hindered by lack of cathode materials. Conversion-type compounds or elemental Se materials break the limit of intercalation mechanism and provide more selections with high capacities. However, conversion compounds often show low reaction reversibility and elemental Se suffers from serious dissolution of polyselenides. Herein, a new strategy of binary selenide/elemental Se is developed to design RMB cathodes. A NiSe2/Se composite was fabricated by selenization of the Ni-MOF precursor, with Se uniform distribution in the NiSe2 microspheres. The elemental Se not only provides extra capacity but also improves the conversion reversibility of NiSe2. Furthermore, the NiSe2 microspheres confine polyselenides, significantly optimizing the cycleability of elemental Se. The NiSe2/Se electrode shows a reversible capacity of 211 mAh/g at 50 mA g−1, a high rate performance of 104 mAh/g at 1.0 A/g, as well as a stable capacity of 132 mAh/g at 200 mA g−1 (retention rate of 80.3 %) after 300 cycles. A mechanism study confirms that both of NiSe2 and Se undergo reversible conversion reaction with Mg2+. The binary selenide/elemental Se cooperative strategy herein delivers a new insight into the exploration of high-performance RMB cathodes.

2D Nanozymes Modulate Gut Microbiota and T-Cell Differentiation for Inflammatory Bowel Disease Management.

Intestinal commensal microbiota dysbiosis and immune dysfunction are significant exacerbating factors in inflammatory bowel disease (IBD). To address these problems, Pluronic F-127-coated tungsten diselenide (WSe2 @F127) nanozymes are developed by simple liquid-phase exfoliation. The abundant valence transitions of elemental selenium (Se2- /Se4+ ) and tungsten (W4+ /W6+ ) enable the obtained WSe2 @F127 nanozymes to eliminate reactive oxygen/nitrogen species. In addition, the released tungsten ions are capable of inhibiting the proliferation of Escherichia coli. In a model of dextran sodium sulfate-induced colitis, WSe2 @F127 nanozymes modulate the gut microbiota by increasing the abundance of bacteria S24-7 and significantly reducing the abundance of Enterobacteriaceae. Moreover, WSe2 @F127 nanozymes inhibit T-cell differentiation and improve intestinal immune barrier function in a model of Crohn's disease. The WSe2 @F127 nanozymes effectively alleviate IBD by reducing oxidative stress damage, modulating intestinal microbial populations, and remodeling the immune barrier.

Microbial-Based Biotechnology: Production and Evaluation of Selenium-Tellurium Nanoalloys

Using seleno-compounds and telluric compounds is a practical approach for developing solutions against drug-resistant bacterial infections and malignancies. It will accelerate the search for novel treatments or adjuvants for existing therapies. Selenium and tellurium nanospheres can be produced by lactic acid bacteria. The bacteria can differentiate the selenium and tellurium when the medium contains both selenite and tellurite. Therefore, our question in this study was the following: are they making alloys from the selenium and tellurium and what will be the composition, color, and shape of the nanoparticles? We used a simple microbial synthesis to produce nanoselenium, nanotellurium, and their alloys from sodium selenite and sodium tellurite using Lactobacillus casei. This bacterium produced red spherical amorphous elemental selenium nanospheres with a diameter of 206 ± 33 nm from selenite and amorphous black nanorods with a length of 176 ± 32 nm and a cross-section of 62 ± 13 nm from tellurite. If the initial medium contains a mixture of selenite and tellurite, the resulting nanoparticles will contain selenium and tellurium in the same ratios in the alloy as in the medium. This proves that Lactobacillus casei cannot distinguish between selenite and tellurite. The shape of the nanoparticles varies from spherical to rod-shaped, depending on the ratio of selenium and tellurium. The color of nanomaterials ranges from red to black, depending on the percentage of selenium and tellurium. These nanomaterials could be good candidates in the pharmaceutical industry due to their antipathogenic and anticarcinogenic properties.

Application of Se-Met to CdTe QDs significantly reduces toxicity by modulating redox balance and inhibiting apoptosis

Cadmium tellurium quantum dots (CdTe QDs) as one of the most widely used QDs have been reported the toxicity and biosafety in recent years, little work has been done to reduce their toxicity however. Based on the mechanisms of toxicity of CdTe QDs on liver target organs such as oxidative stress and apoptosis previously reported by other researchers, we investigated the mechanism of action of trace element selenium (Se) to mitigate the hepatotoxicity of CdTe QDs. The experimental results showed that Se-Met at 40–140 μg L−1 could enhance the function of intracellular antioxidant defense system and the molecular structure of related antioxidant enzymes by reduce the production of ROS by 45%, protecting the activity of antioxidants and up-regulating the expression of selenoproteins with antioxidant functions, Gpx1 increase 225% and Gpx4 upregulated 47%. In addition, Se-Met could alleviate CdTe QDs-induced apoptosis by regulating two apoptosis-inducing factors, as intracellular caspase 3/9 expression levels were reduced by 70% and 87%, decreased Ca2+ concentration, and increased mitochondrial membrane potential measurements. Overall, this study indicates that Se-Met has a significant protective effect on the hepatotoxicity of CdTe QDs. Se-Met can be applied to the preparation of CdTe QDs to inhibit its toxicity and break the application limitation.

Controlling Selenization Equilibrium Enables High-Quality Kesterite Absorbers for Efficient Solar Cells

Kesterite Cu2ZnSn(S, Se)4 is considered one of the most competitive photovoltaic materials due to its earth-abundant and nontoxic constituent elements, environmental friendliness, and high stability. However, the preparation of high-quality Kesterite absorbers for photovoltaics is still challenging for the uncontrollability and complexity of selenization reactions between metal element precursors and selenium. In this study, we propose a solid-liquid/solid-gas (solid precursor and liquid/vapor Se) synergistic reaction strategy to precisely control the selenization process. By pre-depositing excess liquid selenium, we provide the high chemical potential of selenium to facilitate the direct and rapid formation of the Kesterite phase. The further optimization of selenium condensation and subsequent volatilization enables the efficient removal of organic compounds and thus improves charge transport in the absorber film. As a result, we achieve high-performance Kesterite solar cells with total-area efficiency of 13.6% (certified at 13.44%) and 1.09 cm2-area efficiency of 12.0% (certified at 12.1%).

Markovnikov vs anti-Markovnikov iodine-mediated acyloxyselenenylation of alkenes and dienes with elemental selenium and carboxylic acids

The iodine-mediated one-pot synthesis of new bis(β-acyloxyorganyl)selenides from elemental selenium, olefins and carboxylic acids has been developed. The reaction with terminal alkenes leads to the selenides of the Markovnikov type. In the presence of NaOH the regioselectivity of the reaction is changed in favor of the formation of the anti-Markovnikov adducts. With 1,4-cyclohexadiene, the reaction proceeds via addition to only one double bond to afford selenobis(cyclohex-4-ene-2,1-diyl) dibutyrate, whereas with 1,5-cyclooctadiene the bicyclic monoadduct, 9-selenabicyclo[3.3.1]nonane-2,6-diyl dibutyrate, is formed. The mechanism explaining the different regioselectivity is proposed and supported by theoretical calculations.

Silver-Mediated Intermolecular [2 + 2 + 1] Cyclization of Terminal Alkynones with Elemental Selenium: Regioselective Synthesis of 2,4- or 3,4-Dicarbonylselenophenes.

An efficient and atom-economical silver-mediated [2 + 2 + 1] cyclization protocol for the selective synthesis of 2,4- or 3,4-dicarbonylselenophenes has been developed. Readily accessible substrates, commercially available elemental selenium, and good functional group tolerance make this procedure attractive for the selective synthesis of dicarbonylselenophenes. Preliminary mechanistic investigations indicated that silver acetylene species are possible intermediates for the formation of 3,4-dicarbonylselenophenes.

Make Selenium Reactive Again: Activating Elemental Selenium for Synthesis of Metal Selenides Ranging from Nanocrystals to Large Single Crystals.

The inertness of elemental selenium is a significant obstacle in the synthesis of selenium-containing materials at low reaction temperatures. Over the years, several recipes have been developed to overcome this hurdle; however, most of the methods are associated with the use of highly toxic, expensive, and environmentally harmful reagents. As such, there is an increasing demand for the design of cheap, stable, and nontoxic reactive selenium precursors usable in the low-temperature synthesis of transition metal selenides with vast applications in nanotechnology, thermoelectrics, and superconductors. Herein, a novel synthetic route has been developed for activating elemental selenium by using a solvothermal approach. By comprehensive 77Se NMR, Raman, and infrared spectroscopies and gas chromatography-mass spectrometry, we show that the activated Se solution contained HSe-, [Se-Se]2-, and Se2- ions, as well as dialkyl selenide (R2Se) and dialkyl diselenide (R-Se-Se-R) species in dynamic equilibrium. This also corresponded to the first observation of naked Se22- in solution. The versatility of the developed Se precursor was demonstrated by the successful synthesis of (i) the polycrystalline room-temperature modification of the β-Ag2Se thermoelectric material; (ii) large single crystals of superconducting β-FeSe; (iii) CdSe nanocrystals with different particle sizes (3-10 nm); (iv) nanosheets of PtSe2; and (v) mono- and dibenzyl selenides and diselenides at room temperature. The simplicity and diversity of the developed Se activation method holds promise for applied and fundamental research.

Effect of SeO2 on corrosion resistance of micro-arc oxidation

ABSTRACT In order to make titanium alloy implants have better corrosion resistance in the human body, selenium-containing coating was added to the surface of Ti6Al7Nb through micro-arc oxidation. The results indicate that the coating has a higher thickness and lower roughness after the addition of selenium element. XRD, SEM, and XPS analysis showed that selenium element was successfully added into the coating. Then the dynamic polarization curve and EIS indicate that the prepared samples have better corrosion resistance in SBF solution compared to the unadded samples, (i corr ) and (E corr ) are 2.695 × 10−8 A·cm−2 and 0.101 V, respectively. The addition of selenium helps to improve the biological corrosion resistance of the sample in body fluids.

Combined copper and zinc deficiency is associated with reduced SARS-CoV-2 immunization response to BNT162b2 vaccination

The essential trace elements copper, selenium and zinc are of relevance for immunity and immune response to vaccination. In this longitudinal study, adult healthcare workers (n = 126) received two doses of an mRNA vaccine (BNT162b2), and longitudinal serum samples were prepared. Vaccine-induced antibodies and their neutralizing activity were analyzed, and the trace elements copper, zinc, and selenium along with the copper transporter ceruloplasmin were measured. Subjects with combined deficiency of copper and zinc, i.e. both in the lowest tertiles at baseline, displayed particularly low antibody titers at three (Double Q1: 13 AU/mL vs. not double Q1: 29 AU/mL) and six (Double Q1: 200 AU/mL vs. not double Q1: 425 AU/mL) weeks after vaccination (p < 0.05). The results indicate the potential importance of an adequate trace element status of copper and zinc for raising a strong vaccine-induced SARS-CoV-2 antibody response, and highlights the importance of considering combined micronutrient insufficiencies, as single deficiencies may synergize.

Carboxymethyl starch as a reducing and capping agent in the hydrothermal synthesis of selenium nanostructures for use with three-dimensional-printed hydrogel carriers.

The hydrothermal method is a cost-effective and eco-friendly route for preparing various nanomaterials. It can use a capping agent, such as a polysaccharide, to govern and define the nanoparticle morphology. Elemental selenium nanostructures (spheres and rods) were synthesized and stabilized using a tailor-made carboxymethyl starch (CMS, degree of substitution = 0.3) under hydrothermal conditions. CMS is particularly convenient because it acts simultaneously as the capping and reducing agent, as verified by several analytical techniques, while the reaction relies entirely on green solvents. Furthermore, the effect of sodium selenite concentration, reaction time and temperature on the nanoparticle size, morphology, microstructure and chemical composition was investigated to identify the ideal synthesis conditions. A pilot experiment demonstrated the feasibility of implementing the synthesized nanoparticles into vat photopolymerization three-dimensional-printed hydrogel carriers based on 2-hydroxyethyl methacrylate (HEMA). When submersed into the water, the subsequent particle release was confirmed by dynamic light scattering (DLS), promising great potential for use in bio-three-dimensional printing and other biomedical applications.

Electrosynthesis and characterization of alloyed CdSxSe1−x ternary quantum dots

CdS, CdSe and CdSxSe1−x (x = 0.15, 0.35, 0.5, 0.65, 0.85) ternary quantum dots (QDs) were electrosynthesized in a cavity cell and aqueous medium, using 3-mercaptopropionic acid (MPA) as stabilizer. The electrochemical procedure was carried out by a paired electrolysis, where elemental sulfur and selenium were reduced in a graphite powder macroelectrode while a sacrificial cadmium rod was oxidized, giving the simultaneous generation of S2-, Se2- and Cd2+ ions for efficient production of the ternary QDs, in the S2-/Se2- ratio of choice. The CdSxSe1−x QDs were characterized by XRD, HRTEM, UV-Vis absorption and emission spectroscopies, and voltammetric analyses. XRD analysis showed lattice parameters of the cubic CdSxSe1−x nanoalloys with a linear drop tendency when the sulfide molar ratio increased in the crystalline structure. HRTEM analysis was used to determine nanoparticle sizes: 3.94 ± 0.70 nm (CdS), 4.23 ± 1.00 nm (CdS0.5Se0.5), and 4.12 ± 0.78 nm (CdSe), with interplanar distances of 0.348 nm, 0.341 nm, and 0.339 nm, respectively. The band gap energy (Eg opt) of the CdSxSe1−x QDs were determined by UV-Vis absorption spectroscopy: 2.42, 2.47, 2.53, 2.66, 2.63, 2.73 and 2.84 eV, respectively, showing a linear increasing according to the S2-/Se2- ratio. The same behavior was observed for the Eg Elect determined by cyclic and linear voltammetry analysis, presenting a nanoalloy nature of the ternary QDs electrosynthesized.

Characterization of green synthesized selenium nanoparticles (SeNPs) in two different indigenous halophilic bacteria

BackgroundIn the biological method, using nonpathogenic and extremophile bacteria systems are not only safe and highly efficient but also a trump card for synthesizing nanoparticles. Halomonas elongata QW6 IBRC-M 10,214 (He10214) and Salinicoccus iranensis IBRC-M 10,198 (Si10198), indigenous halophilic bacteria, can be used for synthesizing selenium nanoparticles (SeNPs).MethodsSeNP biosynthesis was optimized in two halophilic bacteria and characterized by UV–Vis, Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), X-ray powder diffraction (XRD), zeta potential, and energy dispersive X-ray (EDX).ResultsOptimized conditions for synthesizing SeNPs was at 300 °C at 150 rpm for 72 h and 6 mM or 8 mM concentration of Na2SeO3. UV–Vis indicated a sharp absorption peak at 294 nm. Spherical-shaped nanoparticles by a diameter of 30–100 nm were observed in FESEM and TEM microscopy images. The produced SeNPs were identified by a peak in FTIR spectra. In XRD analysis, the highest peak diffraction had a relationship with SeNPs. The zeta potential analysis showed SeNP production, and elemental selenium was confirmed by EDX.ConclusionsHalophilic bacteria, owing to easy manipulation to create optimization conditions and high resistance, could serve as appropriate organisms for the bioproduction of nanoparticles. The biological method, due to effectiveness, flexibility, biocompatibility, and low cost, could be used for the synthesis of reproducible and stable nanoparticles.

Formation of Red Elemental Selenium from Seleniferous Oxyanions: Deoxygenation by a Homogeneous Iron Catalyst.

Seleniferous oxyanions are groundwater contaminants from both anthropogenic and natural sources, while pure amorphous selenium nanoparticles have a variety of industrial applications. Biology can achieve the multicomponent 6 e-/8 H+ reduction of selenate to amorphous selenium using multiple metalloenzymes, like selenate and selenite reductase. Inspired by biology, we developed a new homogeneous system that can generate pure elemental selenium with no caustic waste. The stoichiometric reductions of selenate, selenite, and selenium dioxide with an iron(II) complex produced an iron(III)-oxo and red elemental selenium, the latter of which has been characterized by a variety of spectroscopic techniques. The catalytic reduction of SeO42- and SeO32- directly to amorphous Se and isolated as Se=PPh3 is reported with a turnover number of 12 and 7, respectively.

Bioactivity of selenium-containing pyridinium salts: Prospecting future pharmaceutical constituents to treat liver diseases involving oxidative stress.

Redox imbalance leads to oxidative stress that causes irreversible cellular damage. The incorporation of the antioxidant element selenium (Se) in the structure of pyridinium salts has been used as a strategy in chemical synthesis and can be useful in drug development. We investigated the antioxidant activity of Se-containing pyridinium salts (named Compounds 3A, 3B, and 3C) through in vitro tests. We focused our study on liver protein carbonylation, liver lipoperoxidation, free radical scavenging activity (1,1-diphenyl-2-picryl-hydrazil [DPPH]; 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid [ABTS]), and enzyme-mimetic activity assays (glutathione S-transferase [GST]-like; superoxide dismutase [SOD]-like). In addition, 2-(4-chlorophenyl)-2-oxoethyl)-2-((phenylselanyl)methyl)pyridin-1-ium bromide (3C) was selected to evaluate the acute oral toxicity in mice due to the best antioxidant profile. The three compounds were effective in reducing the levels of protein carbonylation and lipoperoxidation in the liver in a µM concentration range. All compounds demonstrated scavenger activity of DPPH and ABTS radicals, and GST-like action. No significant effects were detected in the SOD-like assay. Experimental data also showed that the acute oral treatment of mice with Compound 3C (50 and 300 mg/kg) did not cause mortality or change markers of liver and kidney functions. In summary, our findings reveal the antioxidant potential of Se-containing pyridinium salts in liver tissue, which could be related to their radical scavenging ability and mimetic action on the GST enzyme. They also demonstrate a low toxicity potential for Compound 3C. Together, the promising results open space for future studies on the therapeutic application of these molecules.

Growth and characterization of Bi2Te2.70Se0.30 nanostructured materials by using a cost-effective chemical solution route

A chemical solution route was employed to successfully synthesize single-phase Bi2Te2.70Se0.30 nanostructured powders at room temperature, ensuring minimal contamination. The synthesized powders underwent a comprehensive analysis using a range of characterization techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive analysis of X-ray (EDAX), ultraviolet-visible (UV) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, atomic-force microscopy (AFM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The temperature-dependent behaviors of electrical conductivity and the Seebeck coefficient were also explored. The findings revealed that the synthesized powders displayed consistent spherical morphology, with an average diameter of 68.42 nm. Additionally, they exhibited a band gap energy of 0.615 eV. This research highlights the significant improvement achieved by incorporating selenium into the Bi2Te2.70Se0.30 materials through this synthesis process. The EDAX analysis confirmed the stoichiometric atomic ratio of bismuth (Bi), tellurium (Te), and selenium (Se) elements. Furthermore, the TEM images revealed the presence of agglomeration within the powders, demonstrating a primary crystalline size characterized by relatively small dimensions. The emergence of a pronounced exothermic peak at around 650 K signaled the commencement of oxidation for the Bi2Te2.70Se0.30 material. In electrical measurement, a synergy was achieved between heightened electrical conductivity and a well-matched Seebeck coefficient, with the goal of enhancing energy conversion efficiency in TE applications. These findings demonstrate the potential of the synthesized powders for producing nanostructured thermoelectric (TE) materials with controlled grain sizes, which are essential for the fabrication of high-performance thermoelectric generators (TEGs).

Conversion mechanism of selenium on activated carbon surface: Experimental and density functional theory study

The mechanism of SeO2 capture by activated carbon (AC) was explored via combining experiments with density functional theory (DFT). Adsorption experiments confirmed that after mass loss coefficient correction of AC, the selenium capture capacity of AC reached 7.76 mg/g at 350 °C. AC reached a saturated selenium removal capacity of 9.93 mg/g at 50 min. The weight loss curve recorded the temperature window of selenium desorption on AC surface at about 305 °C. The XPS spectrum revealed that the decomposition and reduction behavior of SeO2 on the AC surface promoted the existence of selenium in the form of Se0. DFT calculations showed that SeO2 was chemically adsorbed on the typical Armchair and Zigzag surfaces of AC, and the adsorption energies of the most stable structures were − 89.77 and − 235.12 kcal/mol, respectively. The effect of temperature on selenium capture via AC was studied by thermodynamic and kinetic analysis. Temperature increase promoted the decomposition and reduction of SeO2 on the AC surface. Kinetic analysis further confirmed that the transformation of Se4+→Se0 was more dominated by decomposition behavior. A part of SeO2 in the gas phase was reduced to Se0 by CO and enriched on AC as elemental selenium.

A Review of Selenium (Se) Nanoparticles: From Synthesis to Applications

AbstractSelenium is an essential trace element that plays a crucial role in various physiological activities, exerting a significant impact on human health. Selenium deficiency can lead to the development of several diseases, while excessive doses can be toxic. In recent years, there is a growing interest in elemental selenium nanoparticles (SeNPs) due to their good biocompatibility, low toxicity, and high antioxidant activity, making them suitable for numerous applications. The quest for enhancing efficacy and reducing toxicity has driven extensive research on SeNPs. This review aims to provide a comprehensive summary of the recent advancements made in the synthesis, characterization, properties, and applications of SeNPs. Moreover, the challenges associated with SeNPs research, as well as the future trends in the field, are thoroughly discussed. This review aims to provide an insight into the current state of research on SeNPs and highlight areas that require further exploration and development.

Synthesis of Benzoselenophenes via TMSCN-Enabled Radical-Mediated Tandem Reaction Involving Enamides and Elemental Selenium.

This study presents a TMSCN-enabled tandem reaction involving enamides and elemental selenium to access a diverse array of benzoselenophenes. Notably, this methodology involves the direct 2-fold C(sp2)-H bond activation without the need for preinstalled halides or boronic acids as reaction handles. The protocol offers several noteworthy features, including the absence of transition metals and strong oxidants, high reaction efficiency, broad substrate scopes, and the use of stable elemental selenium as a selenium source.