Se Nanoparticles Research Articles

Effect of dietary supplementation of selenium nanoparticles on growth performance and nutrient digestibility of common carp (Cyprinus carpio Linnaeus 1758) fingerlings fed sunflower meal based diet

Sunflower meal based diet supplemented with selenium nanoparticles (Se NPs) atlevels of 0, 1, 2, 3, 4 and 5 mg kg-1 were fed common carp (Cyprinus carpio Linnaeus 1758) fingerlings in a seventy days feeding trial, to examine the effects on growth, nutrient digestibility and heamatology. Triplicate tanks were used and each tank contained 15 fingerlings that were subjected to experimental feeding at 4% of their live wet weight. A non-digestible marker, chromic oxide was added in the feed at 1% level. Growth performance in terms of weight gain %, feed conversion ratio (FCR) and specific growth rate (SGR) as well as nutrient digestibility (crude protein, crude fat, gross energy) were estimated following standard methods/standard formulae. Maximum weight gain% (210%), SGR (1.26) and best FCR (1.26) as well as highest nutrient digestibility (crude protein 71%, crude fat 72% and gross energy 70%) were observed in fish fed test diet III supplemented with 2 mg kg-1 Se NPs These results showed that, Se nanoparticles supplementation at the rate of 2 mg kg-1 level is beneficial for improvement of growth in C. carpio fingerlings.

Impact of Selenium and Copper Nanoparticles on Yield, Antioxidant System, and Fruit Quality of Tomato Plants.

The effects of nanoparticles (NPs) on plants are contrasting; these depend on the model plant, the synthesis of the nanoparticles (concentration, size, shape), and the forms of application (foliar, substrate, seeds). For this reason, the objective of this study was to report the impact of different concentrations of selenium (Se) and copper (Cu) NPs on yield, antioxidant capacity, and quality of tomato fruit. The different concentrations of Se and Cu NPs were applied to the substrate every 15 days (five applications). The yield was determined until day 102 after the transplant. Non-enzymatic and enzymatic antioxidant compounds were determined in the leaves and fruits as well as the fruit quality at harvest. The results indicate that tomato yield was increased by up to 21% with 10 mg L−1 of Se NPs. In leaves, Se and Cu NPs increased the content of chlorophyll, vitamin C, glutathione, 2,2′-azino-bis(3-ethylbenzthiazolin-6-sulfonic acid (ABTS), superoxide dismutase (SOD), glutathione peroxidase (GPX) and phenylalanine ammonia liasa (PAL). In fruits, they increased vitamin C, glutathione, flavonoids, firmness, total soluble solids, and titratable acidity. The combination of Se and Cu NPs at optimal concentrations could be a good alternative to improve tomato yield and quality, but more studies are needed to elucidate their effects more clearly.

Multifunctional S-Nitroso-N-acetylpenicillamine-Incorporated Medical-Grade Polymer with Selenium Interface for Biomedical Applications.

Modern crises in implantable or indwelling blood-contacting medical devices are mainly due to the dual problems of infection and thrombogenicity. There is a paucity of biomaterials that can address both problems simultaneously through a singular platform. Taking cues from the body's own defense mechanism against infection and blood clotting (thrombosis) via the endogenous gasotransmitter nitric oxide (NO), both of these issues are addressed through the development of a layered S-nitroso-N-acetylpenicillamine (SNAP)-doped polymer with a blended selenium (Se)-polymer interface. The unique capability of the SNAP-Se-1 polymer composites to explicitly release NO from the SNAP reservoir as well as generate NO via the incorporated Se is reported for the first time. The NO release from the SNAP-doped polymer increased substantially in the presence of the Se interface. The Se interface was able to generate NO in the presence of S-nitrosoglutathione (GSNO) and glutathione (GSH), demonstrating the capability of generating NO from endogenous S-nitrosothiols (RSNO). Scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) traced distribution of elemental Se nanoparticles on the interface and the surface properties were evaluated by surface wettability and roughness. The SNAP-Se-1 efficiently inhibited the growth of bacteria and reduced platelet adhesion while showing minimal cytotoxicity, thus potentially eliminating the risks of systemic antibiotic and blood coagulation therapy. The SNAP-Se-1 exhibited antibacterial activity of ∼2.39 and ∼2.25 log reductions in the growth of clinically challenging adhered Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. SNAP-Se-1 also significantly reduced platelet adhesion by 85.5% compared to corresponding controls. A WST-8-based cell viability test performed on NIH 3T3 mouse fibroblast cells provided supporting evidence for the potential biocompatibility of the material in vitro. These results highlight the prospective utility of SNAP-Se-1 as a blood-contacting infection-resistant biomaterial in vitro which can be further tuned by application specificity.

Se Nanoparticles Induce Changes in the Growth, Antioxidant Responses, and Fruit Quality of Tomato Developed under NaCl Stress.

Nanotechnology represents an opportunity to improve the use of elements in agriculture. Selenium is an element that is beneficial to plants and essential to the human diet. The size of nanoparticles gives them characteristics that can enhance the benefits that selenium provides to plants. The objective of the present study was to determine the effects of selenium nanoparticles on the growth, antioxidant responses, and fruit quality of tomato developed under NaCl stress. Four doses of selenium nanoparticles (1, 5, 10, and 20 mg L−1) under NaCl stress, only NaCl, and a control were evaluated. The results showed that the impact of salinity on the growth of the tomato crop can be reduced with the application of selenium nanoparticles. However, the amount of both enzymatic and non-enzymatic compounds significantly increased in the leaves and fruits of tomato. The results suggest that the application of selenium nanoparticles generated a positive effect against salinity in the tomato crop; moreover, it had a positive impact on the content of beneficial biocompounds for human health in tomato fruits.

Eco‐Friendly Approach to Synthesize Selenium Nanoparticles: Photocatalytic Degradation of Sunset Yellow Azo Dye and Anticancer Activity

AbstractThis report has two principal goals. First, to synthesis Se nanoparticles (Se‐NPLs) via a green approach. Secondly, to explore the photocatalytic activity of Se‐NPLs towards the decolorization of sunset yellow (SSY) azo‐dye and to test its activity against some types of human cancers. Green synthesis of Se‐NPLs from the leaf extracts of Drumstick was developed. Bio‐synthesized Se‐NPLs were characterized using FTIR, UV‐vis, photoluminescence (PL), X‐ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive analysis X‐ray (EDAX) and transmission electron microscopy (TEM) analyses. The UV‐vis absorption maximum between 200 and 400 nm was due to the formation of SPR of Se‐NPLs. FTIR revealed the Se‐NPLs were synthesized, capped and stabilized with bio‐molecules present in the plant extracts. Se‐NPLs exhibited an excitation peak at 399 nm and produced an emission peak at 599 nm. EDAX profile provided a signal of atomic Se (1.45 Kev). XRD confirmed the crystalline nature of Se‐NPLs. SEM and TEM observations show that spherical Se particles appeared with diameters ranging from 23 to 35 nm. A possible mechanism of the reduction of (SeO32−) to (Se0) was discussed. The electrical conductivity was measured with temperature and the activation energy was calculated. The photocatalytic study conducted that Se‐NPLs have the efficiency to degrade sunset yellow dye and the mechanism of degradation has been proposed. Se‐NPLs have been shown to be effective against three types of human cancers (Caco‐2 cells, HepG2 cells, and Mcf‐7 cells). Se‐NPLs are potent anticancer and inhibit the growth of the three cancer cells as indicated by the IC50 values. To conclude, the green‐synthesized Se‐NPLs may be a candidate for further evaluation as a chemotherapeutic agent for some human cancer treatment.

Reduction of selenite to elemental Se(0) with simultaneous degradation of phenol by co-cultures of Phanerochaete chrysosporium and Delftia lacustris.

The simultaneous removal of phenol and selenite from synthetic wastewater was investigated by adopting two different co-culturing techniques using the fungus Phanerochaete chrysosporium and the bacterium Delftia lacustris. Separately grown biomass of the fungus and the bacterium (suspended co-culture) was incubated with different concentrations of phenol (0-1,200 mg/L) and selenite (10 mg/L). The selenite ions were biologically reduced to extracellular Se(0) nanoparticles (3.58 nm diameter) with the simultaneous degradation of up to 800 mg/L of phenol. Upon growing the fungus and the bacterium together using an attached growth co-culture, the bacterium grew as a biofilm onto the fungus. The extracellularly produced Se(0) in the attached growth co-culture had a minimum diameter of 58.5 nm. This co-culture was able to degrade completely 50 mg/L phenol, but was completely inhibited at a phenol concentration of 200 mg/L.

Biosynthesis of Polysaccharides-Capped Selenium Nanoparticles Using Lactococcus lactis NZ9000 and Their Antioxidant and Anti-inflammatory Activities.

Lactococcus lactis (L. lactis) NZ9000, which has been genetically modified, is the most commonly used host strain for nisin regulated gene expression. Selenium (Se) is an essential trace element in the diet of humans and animals important for the maintenance of health and growth. Biosynthesized Se nanoparticles (SeNPs) that use microorganisms as a vehicle are uniquely advantages in terms of low costs, low toxicity and high bioavailability. This study was aimed at preparing novel functionalized SeNPs by L. lactis NZ9000 through eco-friendly and economic biotechnology methods. Moreover, its physicochemical characteristics, antioxidant and anti-inflammatory activities were investigated. L. lactis NZ9000 synthesized elemental red SeNPs when co-cultivated with sodium selenite under anaerobic conditions. Biosynthesized SeNPs by L. lactis NZ9000 were mainly capped with polysaccharides and significantly alleviated the increase of malondialdehyde (MDA) concentration, the decrease of glutathione peroxidase (GPx) and total superoxide dismutase (T-SOD) activity in porcine intestinal epithelial cells (IPEC-J2) challenged by hydrogen peroxide (H2O2). SeNPs also prevented the H2O2-caused reduction of transepithelial electrical resistance (TEER) and the increase of FITC-Dextran fluxes across IPEC-J2. Moreover, SeNPs attenuated the increase of reactive oxygen species (ROS), the reduction of adenosine triphosphate (ATP) and the mitochondrial membrane potential (MMP) and maintained intestinal epithelial permeability in IPEC-J2 cells exposed to H2O2. In addition, SeNPs pretreatment alleviated the cytotoxicity of Enterotoxigenic Escherichia coli (ETEC) K88 on IPEC-J2 cells and maintained the intestinal epithelial barrier integrity by up-regulating the expression of Occludin and Claudin-1 and modulating inflammatory cytokines. Biosynthesized SeNPs by L. lactis NZ9000 are a promising selenium supplement with antioxidant and anti-inflammatory activities.

Co doped Ni0.85Se nanoparticles on RGO as efficient electrocatalysts for hydrogen evolution reaction

Tailoring low-cost electrocatalysts with high activity and good stable for hydrogen evolution reaction (HER) is vital to energy harvesting and storage. Herein, Co doped Ni0.85Se nanoparticles supported on reduced graphene oxide (CoNi0.85Se/RGO) were synthesized by a facile one-step hydrothermal method. As expected, the resulting hybrid materials effectively inhibit the aggregation of nanoparticles and possess the enhanced intrinsic conductivity, leading to exposure of more active sites and the faster electron transport. And then these beneficial effects enable CoNi0.85Se/RGO efficient HER catalytic activity in both acid and basic electrolytes, achieving small overpotentials of 148 and 128 mV at a current density of 10 mA cm−2 in 0.5 M H2SO4 and 1.0 M KOH, respectively.

Fungal formation of selenium and tellurium nanoparticles

The fungi Aureobasidium pullulans, Mortierella humilis, Trichoderma harzianum and Phoma glomerata were used to investigate the formation of selenium- and tellurium-containing nanoparticles during growth on selenium- and tellurium-containing media. Most organisms were able to grow on both selenium- and tellurium-containing media at concentrations of 1 mM resulting in extensive precipitation of elemental selenium and tellurium on fungal surfaces as observed by the red and black colour changes. Red or black deposits were confirmed as elemental selenium and tellurium, respectively. Selenium oxide and tellurium oxide were also found after growth of Trichoderma harzianum with 1 mM selenite and tellurite as well as the formation of elemental selenium and tellurium. The hyphal matrix provided nucleation sites for metalloid deposition with extracellular protein and extracellular polymeric substances localizing the resultant Se or Te nanoparticles. These findings are relevant to remedial treatments for selenium and tellurium and to novel approaches for selenium and tellurium biorecovery.

Platelet Selenium Indices as Useful Diagnostic Surrogate for Assessment of Selenium Status in Lambs: an Experimental Comparative Study on the Efficacy of Sodium Selenite vs. Selenium Nanoparticles.

Unlike in human medicine, information on the platelet selenium (Se) concentration and glutathione peroxidase (GPx) activity, as potential biomarkers of Se status, is lacking in the field of veterinary medicine. The aims of this study were to compare the effects of sodium selenite (SeS) and Se nanoparticles (SeN) on platelet Se indices, and compare the results with those of conventional indices of Se status in sheep. Eighteen lambs with marginal Se status were assigned to a control (CON) group and two Se-treated groups administered either a single dose of Se at 0.055mg/kg BW subcutaneously as SeS or SeN. The Se concentration and GPx activity in plasma, erythrocytes, whole blood, and platelets were assessed at 14 time points during 90days. In Se-treated groups, Se concentrations and GPx activity increased significantly in plasma, whole blood, erythrocytes, and platelets. However, the responses in SeS group often started and peaked earlier and, in almost all time points, were more pronounced than the SeN group (P < 0.001), indicating that SeS compared to SeN was more biopotent in raising Se biomarkers. Se indices in platelets started and peaked later than those of short-term (in plasma) and earlier than those of long-term indices (in erythrocytes) indicating that platelet indices can serve as intermediate-term biomarkers of Se status. In conclusion, platelet indices of Se are promising proxy for currently used indices of Se status in sheep, regardless of Se source.

Invitro growth of gut microbiota with selenium nanoparticles.

The application of nanoparticles rose steeply in the last decade, where they have become a common ingredient used in processed human food, improving food properties such as shelf life and appearance. Nanoparticles have also attracted considerable interest to the livestock industry, due to their efficacy in intestinal pathogen control, with the regulatory and consumer driven push for the removal of antibiotic growth promoters. The influence of selenium (Se) nanoparticles was investigated on a diverse and mature broiler caecal microbiota using in vitro culturing and 16S rRNA gene sequencing methods for microbiota characterisation. Caecal microbiota was collected from 4 traditionally grown heritage roosters and grown for 48 h, in the presence and absence of Se nanoparticles, with 2 technical replicates each. The effect of rooster as a biological variable strongly overpowered the effects of nano-Se in the media, resulting in moderate effects on the structure and diversity of the caecal microbial community. However the nanoparticles showed a significant reduction (P < 0.05) in the abundance of an emerging poultry pathogen, Enterococcus cecorum identical operational taxonomic units (OTU), which could be of notable interest in poultry production for targeted E. cecorum control without significant disturbance to the total microbial community.

Selenium nanoparticles: synthesis, characterization and study of their cytotoxicity, antioxidant and antibacterial activity

This report concerns the green synthesis of selenium nanoparticles (Se-NPs) through chemical reduction method using ascorbic acid (Vitamin C) as a reluctant and polyvinyl alcohol (PVA) or chitosan (CS) as stabilizers. Ultraviolet-visible (UV–vis) absorption spectroscopy, dynamic light scattering (DLS), fourier transform infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM) were applied as the main characterization tools. The cytotoxicity of Se-NPs on fibroblast L929 cells was determined by MTT assay. The nanoparticles showed low toxicity toward the investigated cell line which remained more than 50% viable at 170 ppm for 24 h. The in-vitro antioxidant property of the synthesized Se nanoparticles was evaluated by radical scavenging (DPPH) assay. The IC50 values of the nanoparticles were 26.56 and 530 ppm for PVA coated SeNPs (PVA-SeNPs) and CS coated SeNPs (CS–SeNPs), respectively. Finally, the antibacterial activity of Se-NPs was determined on the gram-negative bacteria Escherichia coli, Pseudomonas aeruginosa, and the gram positive bacteria Staphylococcus aureus, Streptococcus epidermidis. The results showed that Se nanoparticles exhibited dose-dependent antibacterial activity against all the four bacterial strains tested. Noticeably, PVA-SeNPs exhibited significant effect against S. epidermidis (MIC 125 ppm) and S. aureus (MIC 125 ppm). The results of this study indicate that Se nanoparticles can be potentially used as antimicrobial and antioxidant agents.

Foliar application of selenium and nano-selenium affects pomegranate (Punica granatum cv. Malase Saveh) fruit yield and quality

This study examined the impact of selenium (Se) (added as Na2SeO4) and Se nanoparticles (N-Se), as a foliar spray, on several growth parameters, mineral content of leaves, yield, physical and biochemical characteristics of pomegranate (Punica granatum L. cv. Malase Saveh). The experiment was conducted over two consecutive years in the northwest of Iran. Se and N-Se were applied once in 2016 and once in 2017 at 1 and 2 μM (Se1 and Se2, N-Se1 and N-Se2, respectively), first at the full-bloom stage and then one month later. Control plants were sprayed with Se-free water. N-Se2 significantly increased the following parameters in the first year (2016) and second year (2017), respectively: leaf area (1.22- and 1.25-fold), chlorophyll content (1.34- and 1.24-fold), number of fruits/tree (1.35- and 1.28-fold), peel thickness (1.33- and 1.27-fold), fruit diameter (1.08- and 1.10-fold), and yield (1.17- and 1.16-fold). N-Se2 significantly increased N (1.23- and 1.22-fold), P (1.36- and 1.44-fold), K (1.08- and 1.11-fold), Ca (1.12- and 1.17-fold), Fe (1.15- and 1.18-fold) and Se (3.33- and 3.25-fold) content in leaves in both years while Zn content was higher after N-Se2 (1.03- and 1.07-fold) and Se1 (1.02- and 1.04-fold) treatments in both years. N-Se2 significantly increased, relative to the control and in the first and second year, respectively, total sugars (1.17- and 1.19-fold), the content of phenolic compounds (1.05- and 1.08-fold), antioxidants (1.23- and 1.25-fold), and anthocyanins (1.23- and 1.27-fold). Se and N-Se treatments enhanced maturity index and decreased fruit cracking. Broadly, our results indicate that a high concentration of N-Se has a greater and more beneficial impact than a low concentration. Future experiments should focus on increasing the concentration of N-Se. These findings can assist in pomegranate fruit production in arid regions.

Microbiological Properties of Microwave-Activated Carbons Impregnated with Enoxil and Nanoparticles of Ag and Se

Microwave-activated carbons from walnut shells (ACMW) were impregnated with Ag and Se nanoparticles and with the Enoxil biologically active preparation, and the microbiological properties of the obtained composites were studied. To increase the functionality of the adsorbent, the activated carbon was oxidized with ozone, resulting in ACMWO containing aliphatic and aromatic carboxylic groups. There was a considerable decrease in the specific surface of the activated carbon after the oxidation process. Nitrogen adsorption was used to determine the structural parameters of the activated carbons. A simultaneous thermal analysis was used to study the thermal behavior of intact and oxidized activated carbons. Infrared spectroscopy was applied to analyze the surface chemistry of the adsorbents. The microbiological activity of the activated carbons was studied using Escherichia coli bacteria and Candida albicans fungi. The kinetic study of the microbiological activity allowed the estimation of the bactericidal/fungicidal action time of the activated carbons.

Biogenic selenium nanoparticles synthesized by Lactobacillus casei ATCC 393 alleviate intestinal epithelial barrier dysfunction caused by oxidative stress via Nrf2 signaling-mediated mitochondrial pathway.

Background: Selenium (Se) can exert antioxidative activity and prevent the body from experiencing oxidative injury. Biogenic Se nanoparticles (SeNPs) synthesized by probiotics possess relatively strong chemical stability, high bioavailability, and low toxicity, this makes them potential Se supplements. Previously, we demonstrated that SeNPs synthesized by Lactobacillus casei ATCC 393 can alleviate hydrogen peroxide (H2O2)-induced human and porcine intestinal epithelial cells' oxidative damage. However, the antioxidant mechanism remains unclear.Methods: The possible antioxidant mechanism and protective effect of SeNPs on intestinal epithelial permeability and mitochondrial function were evaluated by establishing an H2O2-induced oxidative damage model of human colon mucosal epithelial cells (NCM460) and conducting Nrf2 inhibitor interference experiments. Mitochondrial membrane potential (MMP), mitochondrial DNA content, adenosine triphosphate (ATP), ROS, and protein expression levels of Nrf2-related genes were determined. Mitochondrial ultrastructure was visualized by transmission electron microscopy.Results: An amount of 4 μg Se/mL of SeNPs synthesized by L. casei ATCC 393 alleviated increase of ROS, reduced ATP and MMP, and maintained intestinal epithelial permeability in NCM460 cells challenged by H2O2. In addition, SeNPs improved the protein levels of Nrf2, HO-1, and NQO-1. Moreover, SeNPs attenuated the damage of mitochondrial ultrastructure caused by oxidative stress. Nrf2 inhibitor (ML385) abolished the regulatory effect of SeNPs on intracellular ROS production.Conclusion: Data suggest that biogenic SeNPs synthesized by L. casei ATCC 393 can protect the intestinal epithelial barrier function against oxidative damage by alleviating ROS-mediated mitochondrial dysfunction via Nrf2 signaling pathway. Biogenic SeNPs are an attractive candidate for potential Se supplement agent in preventing oxidative stress-related intestinal disease by targeting mitochondria.

Protein (bovine serum albumin) driven copper selenide and copper telluride nanostructures: structural, optical and electrical properties

Copper selenide and copper telluride nanostructures were synthesized using Bovine serum albumin, for the first time, via a facile hydrothermal method. The involvement of different precursors was proposed through a probable reaction mechanism. Moreover, the structural and optical properties of the prepared Cu(2−x)Se and Cu(2−x)Te nanostructures were investigated. The average sizes of the synthesized copper selenide nanoparticles were in the range of 87 ± 24 nm. Variation in size and shape for copper telluride nanostructures gave round shape nanoparticles as well as rods in micro and nano size and average size for small and large round shape nanoparticles were 52 ± 16 nm and 216 ± 27 nm, respectively. More precisely, size-strain plot and the Williamson-Hall analysis methods were adopted to determine the lattice strain and crystalline sizes of the synthesized nanoparticles. The optical band gap energy of prepared nanoparticles estimated from the UV–Vis spectroscopy was 2.95 and 2.32 eV for Cu(2−x)Se and Cu(2−x)Te nanoparticles, indicating quantum confinement effect due to the deviation from bulk materials to the nanoscale. Moreover, the band gap decreased with enhancement of BSA concentration which suggest that the usage of BSA content is important factor and must be optimized for obtaining desired optical band gap. The electrical conductivity for copper selenide and copper telluride was found as 0.048 − 0.064 × 105 S cm−1 and 0.011 − 0.017 × 106 S cm−1 respectively.

Cu 2-x Se Nanoparticles Enhance the Anticancer Activity of Oxaliplatin By Inhibiting Autophagic Degradation

Aim: To confirm Cu2-xSe nanoparticles (NPs) could inhibit autophagic degradation and based on this property to develop a novel therapeutic strategy for cancer treatment. Materials &amp; methods: Transmission electronic microscopy and confocal laser-scanning microscope were used to observe the accumulation of autophagosome. Western blot was used to investigate the expression of autophagy-associated proteins. Chemotherapeutic drug oxaliplatin was cotreatment with Cu2-xSe in vivo and in vitro to study therapeutic efficacy of autophagy caused by Cu2-xSe NPs. Results &amp; conclusion: Cu2-xSe NPs significantly induce autophagosome accumulation in hepatocellular carcinoma cells, and they mainly inhibit the late-stage autophagy degradation through reducing lysosomal cathepsin activity. Moreover, Cu2-xSe NPs enhance the anticancer activity of oxaliplatin in vivo and in vitro through blocking autophagosome degradation.

The effect of laser pulsewidth on the selenium nanoparticles mass yield

High-throughput synthesis of selenium (Se) nanoparticles in the form of colloidal solutions was carried out by 1030 nm laser ablation of a bulk Se target in deionized water and isopropyl alcohol by laser pulses of variable pulse widths (0.3–8.6 ps). The extinction coefficient of the colloidal solutions exhibits an overall decreasing trend with the increase of the laser pulse width in deionized water, also demonstrating a local minimum at 2–4 ps. This can be explained by the growing ablation thresholds, related to the bigger impact of thermal processes during the transition from femto- to picosecond temporal stages.

A simple one-step hydrothermal synthesis of cobalt[sbnd]nickel selenide/graphene nanohybrid as an advanced platinum free counter electrode for dye sensitized solar cell

A nanohybrid comprises of cobalt-nickel selenide (Co0.50Ni0.50Se) nanoparticles dispersed on graphene nanosheets (GN) has been synthesized by a simple one-step hydrothermal method to use as a counter electrode for dye sensitized solar cell (DSSC). The structural changes and the corresponding electrocatalytic properties in terms of cathodic peak current density and charge transfer resistance at the electrode/electrolyte interface for Co0.5Ni0.5Se/GN nanohybrid with respect to the mass ratio between Co0.5Ni0.5Se nanoparticles and graphene nanosheets have been investigated. Co0.5Ni0.5Se/GN0.50 exhibits higher electrocatalytic activity and lower charge transfer resistance than other Co0.5Ni0.5Se/GN nanohybrids and std. platinum (Pt) counter electrodes. Finally, the DSSC fabricated with Co0.5Ni0.5Se/GN0.50 as the counter electrode delivered photo-conversion efficiency (PCE) of 9.42%, which is higher than that of DSSC fabricated with Co0.5Ni0.5Se (7.59%) and std. Pt (7.68%) counter electrodes. This improved electrochemical performance and higher PCE incited by the synergistic effect of Co and Ni in Co0.5Ni0.5Se nanoparticles, as well as Co0.5Ni0.5Se and graphene, could make Co0.5Ni0.5Se/GN0.50 nanohybrid as a promising low-cost Pt-free counter electrode for DSSC.

Survival of selenium-enriched lactic acid bacteria in a fermented drink under storage and simulated gastro-intestinal digestion.

Selenium (Se), which is present as SeCys in seleno-proteins, is involved in cancer prevention, thyroid functioning, and pathogen inhibition. Se is incorporated in the diet through Se-containing foods. Some lactic acid bacteria (LAB) can biotransform selenite (toxic) into Se-nanoparticles (SeNPs) and Se-amino acids. To exert their beneficial properties in the host, bacteria should survive the harsh conditions of the gastrointestinal tract and during food storage. We evaluated whether selenization of LAB influenced bacterial growth and survival during gastrointestinal digestion and after storage when present in a fermented fruit juice-milk (FJM) beverage. Lactobacillus brevis CRL 2051 and Fructobacillus tropaeoli CRL 2034 were grown in MRS with and without selenite, and used to inoculate the FJM matrix. Selenization had no effect on LAB growth (9.54-9.9 log CFU/mL) in the FJM drink. The presence of SeNPs was confirmed for both selenized strains in the FJM beverage; however, the highest Se concentration (100 μg/L) was detected for the fermented beverage with selenized L. brevis. Under storage conditions 1.1 log CFU/ml decrease in cell count of selenized cells of L. brevis was observed, while no effect on cell viability was detected for non-selenized L. brevis or both selenized and control cells of F. tropaeoli. Resistance of L. brevis during digestion of the fermented FJM beverage was not affected by selenization. Contrarily, an increase (1 log CFU/mL) in the resistance of F. tropaeoli was observed when cells were selenized. After digestion, Se was detected in the soluble fraction of the beverage fermented by both strains, being higher for L. brevis (23.6 μg/L). Although selenization did not exert a drastic effect on strains´ survival during storage and digestion, microbial selenization previous to food fermentation could be an interesting tool for Se enrichment avoiding thus the addition of toxic Se salts.