Se Modification Research Articles

Modification of a O-acetyl-glucomannan from Dendrobium officinale by selenylation modification and its anti-gastric cancer enhancing activity.

In this study, a homogeneous polysaccharide, named YDOP-1 was isolated form Dendrobium officinale using hot water extraction and ethanol precipitation method. YDOP-1 was characterized to be a typical O-acetyl-glucomannan with the molecular wight was 13,456 Da. Cell viability and colony forming assay showed that YDOP-1 possess moderate anti-gastric cancer effects. In order to further improve the anti-gastric cancer effects of YDOP-1, a selenium modification on YDOP-1 was performed. Energy dispersive spectrometer (EDS) and X-ray photoelectron spectroscopy (XPS) analysis demonstrated that the Se was successfully introduced into YDOP-1 by forming SeO bonds. Se modification significantly enhanced the anti-gastric cancer effects of YDOP-1, which could effectively inhibit the proliferation of MGC-803 cells via suppressing colony and inducing apoptosis by regulating the apoptosis proteins of Bax, Bcl-2, and Caspase-7. Our results indicated that the Se modified O-acetyl-glucomannan, YDOP-Se, was expected to be useful in the biomedicine field for the gastric cancer treatment.

Modification of Tartary buckwheat flour via steam explosion and the quality characteristics of corresponding gluten-free whole-grain cookies

Steam explosion (SE, at 0.3–0.7 MPa for 3–7 min) was employed to modify the physicochemical properties of Tartary buckwheat (TB) flour, and the eating quality and starch digestibility of corresponding gluten-free whole-grain TB cookies was assessed. The results illustrated that SE enhanced the water-extractable arabinoxylans content in TB flour by 24%–152%. SE increased the random coil content while decreasing the α-helix content, and starch of SE flours had lower relative crystallinity and degree of short-range order. The water-holding capacity significantly increased with SE at moderate conditions. Additionally, SE flours enhanced the spread ratio of the cookies. Compared to cookies made with native TB flour, the digestibility of starch in cookies made with SE flour was significantly lower, and their resistant starch content was higher. The sensory evaluation attributes of SE cookies were superior to those of native cookie in terms of texture, smell, and form attributes. This study elucidates the action mechanism of SE modification on the properties of TB flours and cookies, offering a reference for the application of SE treatment on whole grain processing.

Collaboration in Contradiction: Self-Adaptive Synergistic ROS Generation and Scavenge Balancing Strategies Used for the Infected Wounds Treatment.

The rational utilization of ROS is key to treating infected wounds. Exogenous ROS can destroy bacterial structures, quickly kill bacteria, and inhibit secondary infections. However, excess ROS at the wound will cause a secondary inflammatory response. Acute infections exacerbate this damage by increasing endogenous ROS, complicating the maintenance of ROS homeostasis. Therefore, regulating the balance of ROS production and scavenging in wounds has emerged as a promising strategy for wound treatment. Conventional ROS balancing platforms are mostly based on the " all for one" strategy of functional superposition and lack self-adaptability and integration. To subvert this conventional strategy, this study proposes a "one for all" self-adaptive integrated photodynamic therapy (PDT)-antioxidant model to actively regulate the ROS balance. A gelatin-hyaluronic acid hydrogel embedded with Se-modified cerium dioxide nanoparticles (Gel-HA-Se@CeO2 NPs) is designed for treating infected wounds. The Se@CeO2 NPs serve both as nanoenzymes and photosensitizers(PS). As nanoenzymes, they exhibit catalase and superoxide dismutase activities, converting hydrogen peroxide and superoxide anions into oxygen. As a PS, it synergizes with oxygen under NIR irradiation to rapidly produce singlet oxygen. Additionally, Se modification enhances the PDT effects by disrupting bacterial antioxidant systems. In vitro and in vivo experiments revealed that the ROS balance platform polarizes M1-type macrophages to M2-type macrophages, altering the wound microenvironment from proinflammatory to prohealing. RNA sequencing revealed that this hydrogel accelerated the reconstruction of the vascular network of the wound by activating the PI3K/AKT pathway and increasing VEGF secretion.This strategy is believed to be beneficial not only for infected wounds but also for treating other conditions that involve the regulation of reactive oxygen species, such as tumors and bacterial infections.

Enhanced electrocatalysis of oxygen reduction on Se-Modified platinum single crystal electrodes

Se-modified platinum single-crystal surfaces in the [011¯] zone have been used as model electrocatalysts for the oxygen reduction reaction (ORR). The results show that: (1) the Pt(hkl)-[n(111)×(100)] electrodes display enhanced ORR electrocatalytic activity with Se modification. (2) Se adatoms have a double effect on the ORR kinetics at model Pt electrodes: they enhance the activity on the neighboring sites and inhibit the reaction on the sites in direct contact with the Se adatoms. (3) The hydrophobicity and the altered electronic properties are probably the reasons for the enhanced electrocatalysis for ORR with Se modification. The positive shift of the potential of zero free charge of Pt(hkl)@Se electrodes compared to that of un-modified Pt(hkl) are in agreement with these interpretations. (4) At very low coverages, the promotion effect of Se modification on ORR activity at (100) sites is stronger than that at (111) sites, which is probably due to the more pronounced hydrophobicity of the former.

Industrial grade calcium sulfide modified by selenium for elemental mercury removal from flue gas

Metallic sulfides (MS) adsorption is considered as an effective method to remove Hg0 from coal-fire flue gas. Se modification can significantly improve Hg0 removal process on MS due to the high affinity constant between Se and Hg0. CaS as a production from wet flue gas desulfurization has potential Hg0 removal ability. Therefore, in the present work, Se modified industrial grade CaS was prepared to remove Hg0 and the effect of the ratio of CaS to Se on Hg0 removal process was studied. Characterization results show that Ca1-Se1.7 had the richest porous structure and largest surface area resulting in more available surface active sites. In addition, Ca1-Se1.7 has the highest content of Se−, who can remove Hg0 via Hg0(ad)+Se22-→HgSe+Se2-. As a result, Ca1-Se1.7 has the highest Hg0 removal efficiency of nearly 100 % from 60 ℃ to 100 ℃, and it reaches 85 % even in the presence of 500 ppm SO2. The Hg0 adsorption kinetic was well defined by the pseudo-first-order kinetic model and internal diffusion model, so that Hg0 diffusion especially internal diffusion is the primary controlling step.

Modification of pea dietary fibre by superfine grinding assisted enzymatic modification: Structural, physicochemical, and functional properties

Using the optimal extraction conditions determined by response surface optimisation, the yield of soluble dietary fibre (SDF) modified by superfine grinding combined with enzymatic modification (SE-SDF) was significantly increased from 4.45 % ± 0.21 % (natural pea dietary fibre) to 16.24 % ± 0.09 %. To further analyse the modification mechanism, the effects of three modification methods–superfine grinding (S), enzymatic modification (E), and superfine grinding combined with enzymatic modification (SE)–on the structural, physicochemical, and functional properties of pea SDF were studied. Nuclear magnetic resonance spectroscopy results showed that all four SDFs had α- and β-glycosidic bonds. Fourier transform infrared spectroscopy and X-ray diffraction spectroscopy results showed that the crystal structure of SE-SDF was most severely damaged. The Congo red experimental results showed that none of the four SDFs had a triple-helical structure. Scanning electron microscopy showed that SE-SDF had a looser structure and an obvious honeycomb structure than other SDFs. Thermogravimetric analysis, particle size, and zeta potential results showed that SE-SDF had the highest thermal stability, smallest particle size, and excellent solution stability compared with the other samples. The hydration properties showed that SE-SDF had the best water solubility capacity and water-holding capacity. All three modification methods (S, E, and SE) enhanced the sodium cholate adsorption capacity, cholesterol adsorption capacity, cation exchange capacity, and nitrite ion adsorption capacity of pea SDF. Among them, the SE modification had the greatest effect. This study showed that superfine grinding combined with enzymatic modification can effectively improve the SDF content and the physicochemical and functional properties of pea dietary fibre, which gives pea dietary fibre great application potential in functional foods.

Construction of Stable Oxygen Redox by Electrochemical Activation O–TM–Se in Nickel‐Rich Layered Oxides for Lithium‐Ion Batteries

The irreversible oxygen redox and structural degradation of LiNi0.8Co0.1Mn0.1O2 (NCM811) at a 4.5 V high voltage cause a severe decline in cycling performance for lithium‐ion batteries. In this study, a novel approach is proposed to enhance the anionic redox chemistry and stability of NCM811 cathode material by introducing gaseous selenium. Seβ+ species are selectively adsorbed within oxygen vacancies, leading to the continuous replacement of Oα− to form a stable O–TM–Se bond during deep charging. Furthermore, Selenium modification improves cationic redox efficiency and alleviates Oα− (α < 2) outward migration, increases oxygen vacancy formation energy. The redox activity of oxygen is diminished, facilitating improved reversibility of oxygen redox and effectively inhibiting irreversible oxygen escape. Additionally, Selenium increases the energy barrier for phase transition, effectively suppressing irreversible phase transition and Ni migration. Selenium reacts with escaping oxygen to form SeO2, effectively reducing side reactions during cycling. As a result, the proposed approach significantly inhibits irreversible oxygen release, leading to remarkable cyclic stability with 87.5% capacity retention after 300 cycles at 1C at 4.5 V and maintained 192.9 mAh g−1 after 150 cycles under 60C. The Se modification realizes stability anionic redox strategy to design novel high‐energy‐density cathode materials with superior cycling performance.

Long-chain omega-3 fatty acids, selenium, and mercury in relation to sleep duration and sleep quality: findings from the CARDIA study.

To examine the associations of long-chain omega-3 polyunsaturated fatty acids (LCω3PUFA) intake with sleep quality and duration in a cohort of American young adults, and to explore whether the associations of interest are modified by selenium (Se) and/or mercury (Hg) status. The study sample consisted of 3964 men and women from the longitudinal Coronary Artery Risk Development in Young Adults (CARDIA) study, aged 25.0 ± 3.6 at baseline. Intake of LCω3PUFA was assessed using an interviewer-administered dietary history questionnaire at baseline (1985-1986), Y7 (1992-1993), and Y20 (2005-2006). Toenail Se and Hg concentrations were quantified at Y2 (1987-1988). The outcomes were self-reported sleep quality and sleep duration measured by one question for each at Y15 (2000-2001) and Y20. Generalized estimating equation was used to examine the association between cumulative average intake of LCω3PUFA and sleep measures. Restricted cubic spline was performed to explore the potential non-linear associations of interest. Se and Hg were dichotomized by their median values to examine the potential effect modification of Se and/or Hg. We did not observe any significant associations (linear or non-linear) of LCω3PUFA intake with either sleep quality or duration. Also, no significant association was observed in any subgroup classified by toenail Se and/or Hg concentrations. Similarly, sensitivity analysis indicated that the null associations between LCω3PUFA intake and sleep quality or duration persisted across subgroups classified by race, gender, obesity, or having small children. Findings from this longitudinal analysis did not support the hypothesis that LCω3PUFA intake is associated with sleep quality or sleep duration.

Boosting interfacial charge transfer for alkaline hydrogen evolution via rational interior Se modification

Abstract For electrocatalytic hydrogen evolution reaction (HER) in alkaline media, it is urgently needed to accelerate the generation of H*. Here, using Se doped phosphides inside nitrogen doped carbon (skin-core structure) as catalysts, the HER performance in alkaline electrolyte was improved. The overpotential of 261 mV at 400 mA cm−2 was among the top level reported so far. Based on the combination of experimental results and density functional theory (DFT) calculations, the interior CoSe phase generated by Se modification provides faster charge transfer from the inner to carbon layer, facilitating the rate-determining step (Volmer). Also, the needle-like nanowire array facilitates the H2 desorption at a large current density. Furthermore, a solar-to-hydrogen efficiency up to 10.2% was demonstrated. This work may provide an effective strategy to boost the reaction kinetics via accelerating interfacial charge transfer ability of electrocatalysts.

Superior Oxygen Electrocatalysis on RuSex Nanoparticles for Rechargeable Air Cathodes

AbstractA one‐step, facile supercritical‐ethanol‐fluid synthesis of Se‐modified Ru nanoparticles nucleated on carbon defects is reported, and it is demonstrated that these nanoparticles provide, with >70% efficiency at 1 A g−1, a highly active and reversible oxygen‐reduction/oxygen‐evolution reaction on an air cathode in a nonaqueous electrolyte. The Se modification not only prevents Ru oxidation during charge/discharge cycling, but also improves the catalytic activity by promoting Li2O2 versus Li2O deposited on the Ru particles during discharge. A computational calculation with density functional theory supports the role of a larger electron transfer to the oxygen of Li2O2 adsorbed on a surface layer of RuSe2−δ than on a surface layer of RuO2, thereby shifting the more stable adsorbent from Li2O to Li2O2.

The Association Between Serum Levels of Selenium, Copper, and Magnesium with Thyroid Cancer: a Meta-analysis.

There are conflicting reports on the correlation between serum levels of selenium (Se), copper (Cu), and magnesium (Mg) with thyroid cancer. The purpose of the present study is to clarify the association between Se, Cu, and Mg levels with thyroid cancer using a meta-analysis approach. We searched articles indexed in PubMed published as of January 2015 that met our predefined criteria. Eight eligible articles involving 1291 subjects were identified. Overall, pooled analysis indicated that subjects with thyroid cancer had lower serum levels of Se and Mg, but higher levels of Cu than the healthy controls [Se: standardized mean difference (SMD) = -0.485, 95% confidence interval (95%CI) = (-0.878, -0.092), p = 0.016; Cu: SMD = 2.372, 95%CI = (0.945, 3.799), p = 0.001; Mg: SMD = -0.795, 95%CI = (-1.092, -0.498), p < 0.001]. Further subgroup analysis found lower serum levels of Se in thyroid cancer in Norway [SMD = -0.410, 95%CI = (-0.758, -0.062), p = 0.021] and Austria [SMD = -0.549, 95%CI = (-0.743, -0.355), p < 0.001], but not in Poland (SMD = -0.417, 95%CI = (-1.724, 0.891), p = 0.532]. Further subgroup analysis also found that patients with thyroid cancer had higher serum levels of Cu in China [SMD = 1.571, 95%CI = (1.121, 2.020), p < 0.001] and Turkey [SMD = 0.977, 95%CI = (0.521, 1.432), p < 0.001], but not in Poland [SMD = 3.471, 95%CI = (-0.056, 6.997], p = 0.054]. In conclusion, this meta-analysis supports a significant association between serum levels of Se, Cu, and Mg with thyroid cancer. However, the subgroup analysis found that there was significant effect modification of Se, Cu levels by ethnic, like China and Poland. Thus, this finding needs further confirmation by a trans-regional multicenter study to obtain better understanding of causal relationship between Se, Cu, and Mg with thyroid cancer of different human races or regions.

Effect of Se modification on RuSey/C electrocatalyst for oxygen reduction with phosphoric acid

Carbon-supported Se-modified-Ru catalysts (RuSey/C) were synthesized, and their phosphate adsorption characteristics were evaluated using electrochemical techniques and in-situ X-ray absorption spectroscopy (XAS). When phosphoric acid was added, the ORR activity of unmodified Ru/C decreased by 26.8% because the active sites were blocked by electrochemical adsorption, as confirmed by CV. However, for RuSey/C, the ORR activity was enhanced with phosphoric acid (RuSe1.56/C: 63.8%), which indicates that the kinetics at each site increased to compensate for the site blocking effect. The XAS results demonstrated that, for RuSey/C, phosphoric acid molecules or phosphate anions primarily interacted with Se atoms, and the oxidation state of Ru atoms decreased. Therefore, it was concluded that the enhanced ORR kinetics originated from the decreased oxygen binding energy with larger electrostatic repulsion.

First principles study of oxygen adsorption on Se-modified Ru nanoparticles

We present here the results of our density-functional-theory-based calculations of the electronic and geometric structures and energetics of Se and O adsorption on Ru 93- and 105-atom nanoparticles. These studies have been inspired by the fact that Se/Ru nanoparticles are considered promising electrocatalysts for the oxygen reduction reaction (ORR) on direct methanol fuel cell cathodes and the oxygen binding energy is a descriptor for the catalyst activity toward this reaction. We find the character of chemical bonding of Se on a flat nanoparticle facet to be ionic, similar to that obtained earlier for the Se/Ru(0001) surface, while in the case of a low-coordinated Ru configuration there is an indication of some covalent contribution to the bonding leading to an increase in Se binding energy. Se and O co-adsorbed on the flat facet both accept electronic charge from Ru, whereas the adsorption on low-coordinated sites causes more complicated valence charge redistribution. The Se modification of the Ru particles leads to weakening of the oxygen bonding to the particles. However, overall, O binding energies are found to be higher for the particles than for Se/Ru(0001). The high reactivity of the Se/Ru nanoparticles found in this work is not favorable for ORR. We thus expect that larger particles with well-developed flat facets will be more efficient ORR catalysts than small nanoparticles with a large fraction of under-coordinated adsorption sites.

Nature of the Selenium Submonolayer Effect on the Oxygen Electroreduction Reaction Activity of Ru(0001)

I present here results of first principles studies of the adsorption energetics of the intermediates of the oxygen electroreduction reaction (ORR) on a Se-modified Ru(0001) surface. The calculations were performed for 1/3 and 2/3 monolayer coverage of Se, as well as for clean Ru(0001) as a reference. The binding energies of O and OH on Ru(0001) are found to decrease significantly with the presence of Se, and this effect increases with the Se coverage. The Se surface modification is found not to change the Ru local density of electronic states noticeably. However, Se atoms accept electronic charge from the surface and thus become negatively charged. As a result, they repeal electrostatically the adsorbed negatively charged O and OH intermediates and in this way reduce their binding energies. This effect provides an alternative way of tuning the reactivity of the catalyst surfaces. Since for the Ru case reduction of the O and OH binding energies makes ORR energetically favorable, Se modification dramatically improves the ORR rate on Ru. Adsorption of O2 and coadsorption of the ORR intermediates and water have also been studied. The effect of coadsorption on the binding energies of O and OH are discussed.

Synthesis of 2′-Deoxy-5-(methylselenyl)cytidine and Se-DNAs for Structural and Functional Studies

It's not in your DNA: We report here the synthesis of a novel 5-methyl deoxycytidine analog and its phosphoramidite modified with selenium at the C-5 position (SeC). Incorporation of SeC into DNA does not cause structural perturbations, as shown by X-ray crystallography and in agreement with UV melting data. The Se modification provides a useful strategy for biochemical and structural investigations on 5-methylation of cytidine.

Synthesis and Crystal Structure of 2′-Se-Modified Guanosine Containing DNA

Selenium modification of nucleic acids is of great importance in X-ray crystal structure determination and functional study of nucleic acids. Herein, we describe a convenient synthesis of a new building block, the 2'-SeMe-modified guanosine (G(Se)) phosphoramidite, and report the first incorporation of the 2'-Se-G moiety into DNA. The X-ray crystal structure of the 2'-Se-modified octamer DNA (5'-GTG(Se)TACAC-3') was determined at a resolution of 1.20 A. We also found that the 2'-Se modification points to the minor groove and that the modified and native structures are virtually identical. Furthermore, we observed that the 2'-Se-G modification can significantly facilitate the crystal growth with respect to the corresponding native DNA.

Derivatization of DNAs with selenium at 6-position of guanine for function and crystal structure studies

To investigate nucleic acid base pairing and stacking via atom-specific mutagenesis and crystallography, we have synthesized for the first time the 6-Se-deoxyguanosine phosphoramidite and incorporated it into DNAs via solid-phase synthesis with a coupling yield over 97%. We found that the UV absorption of the Se-DNAs red-shifts over 100 nm to 360 nm (ε = 2.3 × 104 M−1 cm−1), the Se-DNAs are yellow colored, and this Se modification is relatively stable in water and at elevated temperature. Moreover, we successfully crystallized a ternary complex of the Se-G-DNA, RNA and RNase H. The crystal structure determination and analysis reveal that the overall structures of the native and Se-modified nucleic acid duplexes are very similar, the selenium atom participates in a Se-mediated hydrogen bond (Se … H–N), and the SeG and C form a base pair similar to the natural G–C pair though the Se-modification causes the base-pair to shift (approximately 0.3 Å). Our biophysical and structural studies provide new insights into the nucleic acid flexibility, duplex recognition and stability. Furthermore, this novel selenium modification of nucleic acids can be used to investigate chemogenetics and structure of nucleic acids and their protein complexes.

Synthesis of Selenocysteine and Selenomethionine Derivatives from Sulfur‐Containing Amino Acids

Selenium-containing amino acids have attracted increasing interest from view points of the importance as active centers of several selenoenzymes, the biological synthesis, the metabolism, and the use for structure determination of proteins. In this article, our recent progresses in the transformation from sulfur-containing amino acids to selenocysteine (SeCys) and selenomethionine (SeMet) derivatives are reviewed along with the surveys of general organic methodologies for the synthesis of SeCys and SeMet derivatives in the literature. The S-->Se modification (i.e., the chemical atomic mutation) would be a useful approach to peptide synthesis involving selenoamino acid residues.

Modification and modulation of saccharides on elemental selenium nanoparticles in liquid phase

The modification and modulation of saccharides on elemental selenium (Se 0) nanoparticles in liquid phase were studied. The saccharides, such as monosaccharide (glucose), oligosaccharide (sucrose), polysaccharides (chitosan and the eucheuma striatum sulfated polysaccharide (ESSP)), were used as modifiers to modulate the formation rate and assembly of Se 0 nanoparticles in liquid phase. Laser light scattering, transmission electron microscope (TEM) and resonance Rayleigh scattering (RRS) were used to study the function of saccharides in modification and assembly of Se 0 nanoparticles. The results show that the saccharides modulated the Se 0 nanoparticles in the aspects of the diameter, size appearance and stability in the liquid phase. The modulation of saccharides on Se 0 nanoparticles strengthened as the molecular sizes of saccharides increased. The different molecular structure of saccharides had various modulations and modifications on the assembly of the Se 0 nanoparticles. The Se 0-saccharide sol was stable for long time, especially the Se 0-oligosaccharide sol and Se 0-polysaccharide sol.

Oxygen Replacement with Selenium at the Thymidine 4-Position for the Se Base Pairing and Crystal Structure Studies

The T−A and C−G base pairing and stacking allow the formation of the stable DNA duplex structure for genetic information storage, transcription, and replication. To replace the oxygen of the nucleotide nucleobases with selenium for the studies of the base-pair recognition, the duplex stability, and the nuclei acid crystal structures, we have synthesized for the first time the 4-Se thymidine phosphoramidite and incorporated it into oligonucleotides via solid-phase synthesis with high coupling yield (99%). The Se modification on the nucleobase is relatively stable under the elevated temperature. Using the dUSe (2‘-Se-dU) to facilitate the crystallization, we have successfully crystallized the DNA containing the 4-Se−T substitution and determined its structure at 1.50 A resolution. The UV-melting and X-ray crystal structure studies have indicated that the Se substitution on the nucleobase does not cause a significant structure perturbation, the large Se atom on the thymine can be successfully accommodated by...