Antibacterial Activity of Biosynthesized Selenium Nanoparticles Using Extracts of Calendula officinalis against Potentially Clinical Bacterial Strains

The use of selenium nanoparticles (SeNPs) in the biomedical area has been increasing as an alternative to the growing bacterial resistance to antibiotics. In this research, SeNPs were synthesized by green synthesis using ascorbic acid (AsAc) as a reducing agent and methanolic extract of Calendula officinalis L. flowers as a stabilizer. Characterization of SeNPs was performed by UV-vis spectrophotometry, infrared spectrophotometry (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM) techniques. SeNPs of 40–60 nm and spherical morphologies were obtained. The antibacterial activity of marigold extracts and fractions was evaluated by disk diffusion methodology. The evaluation of SeNPs at different incubation times was performed through the colony-forming unit (CFU) count, in both cases against Serratia marcescens, Enterobacter cloacae, and Alcaligenes faecalis bacteria. Partial antibacterial activity was observed with methanolic extracts of marigold leaves and flowers and total inhibition with SeNPs from 2 h for S. marcescens, 1 h for E. cloacae, and 30 min for A. faecalis. In addition, SeNPs were found to exhibit antioxidant activity. The results indicate that SeNPs present a potentiated effect of both antimicrobial and antioxidant activity compared to the individual use of marigold extracts or sodium selenite (Na₂SeO₃). Their application emerges as an alternative for the control of clinical pathogens.     

The Influence of Synthesis Conditions on the Antioxidant Activity of Selenium Nanoparticles

Selenium nanoparticles (SeNPs) have attracted great attention in recent years due to their unique properties and potential bioactivities. While the production of SeNPs has been long reported, there is little news about the influence of reaction conditions and clean-up procedure on their physical properties (e.g., shape, size) as well as their antioxidant activity. This study takes up this issue. SeNPs were synthesized by two methods using cysteine and ascorbic acid as selenium reductants. The reactions were performed with and without the use of polyvinyl alcohol as a stabilizer. After the synthesis, SeNPs were cleaned using various procedures. The antioxidant properties of the obtained SeNPs were investigated using DPPH and hydroxyl radical scavenging assays. It was found that their antioxidant activity does not always depend only on the nanoparticles size but also on their homogeneity. Moreover, the size and morphology of selenium nanoparticles are controlled by the clean-up step.     

Production of single-cell protein with two-step fermentation for treatment of potato starch processing waste

Potato starch processing waste is causing serious environmental problems. This study aimed to convert potato starch processing waste into single-cell protein as high-quality feed using a two-step fermentation process. The mutant strain Aspergillus niger H3 was selected after UV irradiation and ethyl methyl sulfone mutagenesis for more cellulase production. The activities of sodium carboxymethyl cellulase and filter paperase of strain H3 were 8.86 and 4.79 U, respectively, which were much higher than the parent strain (1.18 and 0.62 U). After treatment with strain H3, the cellulose degradation rate of potato residue was 80.54 %. A liquid fermentation using Bacillus licheniformis was performed as the second step. The optimized fermentation conditions were temperature of 32.8 °C, pH 6.67, and inoculum concentration of 1.78 % using the response surface method. Results of this study showed a potential application in large-scale industrial conversion.     

Synthesis,characterization and evaluation of biological properties of selenium nanoparticles from Solanum lycopersicum

Synthesis of nanoparticles by green synthesis has a large number of biomedical applications worldwide. In this study, Selenium Nanoparticles (SeNPs) were synthesized by using sodium salt of selenium and Solanum lycopersicum (tomato) fruit juice and seeds extract. The plant extracts were used as a reducing agent in ratio 1:4 i.e. sodium selenite salt (Na₂SeO₃). SeNPs were characterized by UV–visible spectrophotometry, FTIR and Zeta Sizer analysis. The UV-graphs indicated the highest peak of absorbance at 350 nm. Whereas, FTIR analysis of SeNPs indicated absorbance bands at 3262.35–1633.72 cm^?1. Zeta sizer analysis showed the average size of SeNPs for Fruit juice extract as 1020 d.nm. with PDI 0.432. In case of seeds extract, average size was 1155 d.nm. with PDI 0.761; and the PDI value for both extracts showed polyderse nature of these NPs. SeNPs possessed significant antimicrobial activity against selected strains of E. coli, S. aureus, M. luteus, S. enterica, B. subtilis, K. pneumoniae and P. aureginosa. The α-amylase inhibitory assay of these SeNPs indicated that they had antidiabetic role with IC₅₀ value 24.4642 µg/mL. The DPPH assay showed that SeNPs of Solanum lycopersicum have antioxidant activity with IC₅₀ value of 20.7398 µg/mL.     

High antimicrobial,cytotoxicity, and catalytic activities of biosynthesized selenium nanoparticles using Crocus caspius extract

The green method for synthesizing various nanoparticles is defined as one of the environmentally friendly, promising, and safer technologies. In our study, the selenium nanoparticles (C@SeNPs) were synthesized by Crocus caspius aqueous extract. The existence of functional groups involved in the synthesis of SeNPs that were connected with bioactive compounds was confirmed by the FT-IR spectrum. The TGA curve confirmed about 60 % weight loss between 260 and 500 °C, implying biomolecules surround the metallic core. XRD analysis displayed the trigonal nature of SeNPs. The SEM and TEM images of C@SeNPs demonstrated semi-spherical in shape. EDX analysis identified the intense bond of selenium. Biosynthesized C@SeNPs were discovered to have considerable antioxidant and antibacterial activities on several strains of bacteria. An IC₅₀ value of 67.63 ± 2.5 μg/ml was obtained for their iron-chelating activity. In addition, the fabricated SeNPs have a strong growth inhibitory effect on MCF-7 and AGS cancer cells. C@SeNPs exhibited effective antifungal activity against tested fungi strains and antileishmanial activity against promastigotes. Besides, our NPs were able efficiently to degrade methylene blue (MB) dye in the presence of NaBH₄. Thus, the current findings suggest the benefits of using green technology to synthesize SeNPs with potential activity.     

Green Synthesis of Silver Nanoparticles Using Natural Extracts with Proven Antioxidant Activity

Natural extracts are a rich source of biomolecules that are useful not only as antioxidant drugs or diet supplements but also as complex reagents for the biogenic synthesis of metallic nanoparticles. The natural product components can act as strong reducing and capping substrates guaranteeing the stability of formed NPs. The current work demonstrates the suitability of extracts of Camellia sinensis, Ilex paraguariensis, Salvia officinalis, Tilia cordata, Levisticum officinale, Aegopodium podagraria, Urtica dioica, Capsicum baccatum, Viscum album, and marine algae Porphyra Yezoensis for green synthesis of AgNPs. The antioxidant power of methanolic extracts was estimated at the beginning according to their free radical scavenging activity by the DPPH method and reducing power activity by CUPRAC and SNPAC (silver nanoparticle antioxidant capacity) assays. The results obtained by the CUPRAC and SNAPC methods exhibited excellent agreement (R²~0.9). The synthesized AgNPs were characterized by UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), dynamic light scattering (DLS) particle size, and zeta potential. The UV-vis absorption spectra showed a peak at 423 nm confirming the presence of AgNPs. The shapes of extract-mediated AgNPs were mainly spherical, spheroid, rod-shaped, agglomerated crystalline structures. The NPs exhibited a high negative zeta potential value in the range from −49.8 mV to −56.1 mV, proving the existence of electrostatic stabilization. FTIR measurements indicated peaks corresponding to different functional groups such as carboxylic acids, alcohol, phenol, esters, ethers, aldehydes, alkanes, and proteins, which were involved in the synthesis and stabilization of AgNPs. Among the examined extracts, green tea showed the highest activity in all antioxidant tests and enabled the synthesis of the smallest nanoparticles, namely 62.51, 61.19, and 53.55 nm, depending on storage times of 30 min, 24 h, and 72 h, respectively. In turn, the Capsicum baccatum extract was distinguished by the lowest zeta potential, decreasing with storage time from −66.0 up to −88.6 mM.     

Preparation of chitosan nanoparticles by spray drying,and their antibacterial activity

Chitosan nanoparticles were prepared from chitosan of different molecular weight by spray drying. The morphology of the particles was characterized by SEM, and size distribution and zeta potential were determined. The effects of chitosan solution concentration, molecular weight of chitosan, and size of the spray dryer nozzles on average size, size distribution and zeta potential of chitosan nanoparticles were investigated. The effects of chitosan nanoparticles and chitosan nanoparticles–amoxicillin complex on Staphylococcus aureus were also tested. The results showed that the average size of chitosan nanoparticles were in the range 95.5–395 nm and zeta potentials were 39.3–45.7 mV, depending on the concentration and molecular weight of the chitosan. The lower the concentration and molecular weight of the chitosan, the smaller the chitosan nanoparticles and the higher the zeta potential. Testing for antibacterial activity against S. aureus indicated that chitosan nanoparticles strongly inhibited growth of the bacteria; the minimum inhibitory concentration, 20 μg/mL, was lower than those of chitosan solution or amoxicillin. The antibacterial capacity of chitosan nanoparticles also depended on the size, zeta potential, and molecular weight of the chitosan. Complexation of chitosan nanoparticles with amoxicillin improved the antibacterial activity of amoxicillin.     

亚硒酸钠在L-半胱氨酸自组装类生物膜修饰电极上的电化学行为

利用L-半胱氨酸自组装膜修饰金电极(L-Cys,Au/SAMs), 在0.05mol/L H_2SO_4 底液中研究了 Na_2SeO_3 的电化学特性.在0.00～1.30 V (vs. SCE) 电位范围内对微量Na_2SeO_3进行循环伏安扫描,发现L-Cys, Au/SAMs修饰电极在峰电位0.89 V处有灵敏的Se的氧化溶出峰.通过比较裸金电极和修饰电极在Na_2SeO_3 溶液中的电化学特性发现,修饰电极通过巯基中的S与Na_2SeO_3发生氧化还原作用生成Se,且修饰电极对沉积在电极表面的Se的氧化过程具有催化作用.根据Na_2SeO_3在单分子膜上的电化学行为,提出了单分子膜中硫(Au-S)与Se(Ⅳ)作用生成Se的反应机理、Se电化学催化氧化机理及巯基化合物通过生成纳米硒生物吸收Se的类生物膜模型.     

Purification and Biochemical Characterization of a Novel Thermo-stable Carboxymethyl Cellulase from Azorean Isolate Bacillus mycoides S122C

Bacillus mycoides S122C was identified as carboxymethyl cellulase (CMcellulase)-producing bacteria from the Azorean Bacillus collection (Lab collection), which was isolated from local soil samples. The bacteria was identified by 16S rRNA sequence and designated as B. mycoides S122C. NCBI blast analysis showed that the B. mycoides S122C 16S rRNA sequence has high identity compared to other B. mycoides strains. CMcellulase was purified from the culture filtrates using anion-exchange chromatography. After mono-Q purification, the protein folds and recovery were 13.7 and 0.76?%, respectively. SDS-PAGE analysis showed that the molecular weight of the purified CMcellulase protein was estimated to be about 62?kDa and that it was composed of a single subunit. MALDI-MS/MS analysis yielded each four peptides of the purified protein; it has identity to other cellulases. The purified CMcellulase showed high activity with CMcellulose followed by ??-glucan as a substrate. Optimum temperature and pH for the purified CMcellulase activity were found to be at 50?°C and pH?7.0, respectively. The purified CMcellulase was stable with about 60?% activity in broad pH ranges from 5 to 10 and temperature of 40 to 60?°C. However, purified CMcellulase was stable at about 70?% at 70?°C and also stable overall at 78?% for surfactants. CMcellulase activity was inhibited by ions such as HgCl₂, followed by CuSo₄, FeCl₂, and MnCl₂, while CoCl₂ activated CMcellulase activity. The purified CMcellulase activity was strongly inhibited by EDTA.     

DRC™ ICP-MS coupled with automated flow injection system with anion exchange minicolumns for determination of selenium compounds in water samples

A flow injection system with anion exchange resin minicolumns was coupled with dynamic reaction cell (DRC™) ICP-MS for the determination and speciation of selenite and selenate at sub μg L⁻¹ levels. The charged selenate and uncharged selenite were separated on the first resin column in which only selenate was retained. The unretained selenite was then deprotonated with alkaline solution, and the resulting anionic selenite species was collected on the second column serially connected downstream. By setting a sample loop, total selenium can be determined together with selenite and selenate. The selenium species was eluted by nitric acid and carried to DRC™ ICP-MS for their detection. Using ammonia as reaction gas, the detection of ⁷⁸Se was improved. The enrichment factor was 20 for 10 mL of sample. The standard deviations (n = 5) of peak heights were 4.9%, 4.1%, and 7.0% for a 5.0 × 10⁻² μg L⁻¹ selenite and selenate, and total Se, respectively. The calibration graphs were linear from 2.0 × 10⁻² to 1.0 μg L⁻¹ selenite and selenate. And, the linearity for total selenium was good in the range of 10.0 × 10⁻² to 1.0 μg L⁻¹. The proposed method has been demonstrated for the application to natural and bottled drinking water samples.     

Efficient eco-friendly approach towards bimetallic nanoparticles synthesis and characterization using Exiguobacterium aestuarii by statistical optimization

ABSTRACT

Biogenic synthesis of bimetallic nanoparticles (gold – AuNp and selenium – SeNp) using inexpensive Tryptophan Enriched Banana Peel Media for the growth of marine isolate (Exiguobacterium aestuarii SBG4 MH185868). The response surface methodology is employed for optimizing production conditions. The surface plasmon resonance band showed λ_max at 540?nm (AuNp) and 284?nm (SeNp). FTIR and zeta potential analysis confirmed the stability, whereas XRD spectra revealed the nature of nanoparticles obtained at optimum conditions. SEM micrographs showed nanospheres of the following size: AuN, 30?±?5 nm and SeNp, 50?±?5 nm. Biocompatibility of Np evaluated by the hemolytic activity showed <20% hemolysis even at highest concentrations (100?µg/ml). AuNp showed the least cytotoxicity, whereas SeNp showed considerable cytotoxicity against the breast cancer cell lines MCF – 7 and MDA-MB-231. Hence, we utilized the environment-friendly growth media for the controlled synthesis of dual Np using single bacterial strain involving feasible steps in downstream processing.     

Multifunctional Eco-Friendly Synthesis of ZnO Nanoparticles in Biomedical Applications

This work describes an environmental-friendly preparation of ZnO nanoparticles using aqueous oat extract. The advanced electrochemical and optical features of green synthesized ZnONPs displayed excellent antibacterial activity and exhibited an important role in pharmaceutical determinations. The formation of nanoscale ZnO was confirmed using various spectroscopic and microscopic investigations. The formed nanoparticles were found to be around 100 nm. The as-prepared ZnONPs were monitored for their antibacterial potential against different bacterial strains. The inhibition zones for ZnONPs were found as Escherichia coli (16 mm), Pseudomonas aeruginosa (17 mm), Staphylococcus aureus (12 mm) and Bacillus subtilis (11 mm) using a 30-µg mL⁻¹ sample concentration. In addition, ZnONPs exhibited significant antioxidant effects, from 58 to 67%, with an average IC₅₀ value of 0.88 ± 0.03 scavenging activity and from 53 to 71% (IC₅₀ value of 0.73 ± 0.05) versus the scavenging free radicals DPPH and ABTS, respectively. The photocatalytic potential of ZnONPs for Rhodamine B dye degradation under UV irradiation was calculated. The photodegradation process was carried out as a function of time-dependent and complete degradation (nearly 98%), with color removal after 120 min. Conclusively, the synthesized ZnONPs using oat biomass might provide a great promise in the future for biomedical applications.     

无定形硒纳米粒子的交联酶模板法合成及其在生物传感器中的应用

本文以戊二醛交联的辣根过氧化物酶(HRP)为模板合成了均匀分散的无定形硒纳米粒子(粒径10~20 nm)，以所得合成产物为载体构建了HRP生物传感器。研究结果表明，无定形硒纳米粒子具有良好的生物相容性和吸附性，所得传感器灵敏度高，对测定底物的生物亲和性好。     

Determination of Selenium Species in Cordyceps militaris by High-performance Liquid Chromatography Coupled to Hydride Generation Atomic Fluorescence Spectrometry

The purpose of this work is to develop a high-efficiency extraction method for determining the selenium species in Cordyceps militaris. Six extraction solutions, including hot water, HCl, methanol–water, ammonium acetate, protease XIV, and protease K, combined with ultrasound-assisted extraction, were utilized in the measurements. The selenium species in the extracts were separated and characterized by high-performance liquid chromatography. Their concentrations were subsequently determined by hydride generation atomic fluorescence spectrometry. The 25?mM ammonium acetate was selected as the extraction solution due to its advantages in cost and efficiency. Validation was performed, and the selenium species recoveries were 69–97% for selenocystine, selenite, selenomethionine, and selenate with good linearity and precision. The major selenium species in C. militaris were selenocystine and selenomethionine that accounted for almost 73.1?±?1.6% of the total selenium.     

Electric Double Layer in Water-Organic Mixed Solvents: Titania in 50% Ethylene Glycol

Ethylene glycol (EG) and its mixtures with water are popular components of nanofluids used as heat transfer fluids. The stability of nanofluids against coagulation is correlated with their zeta potential. The electrophoretic mobility of titania nanoparticles in 50-50 w/w EG was studied as a function of the concentration of various solutes. HCl, NaOH, SDS and CTMABr at concentrations up to 0.01 M are strong electrolytes in 50% EG, that is, the conductance of their solutions is proportional to the concentration. HCl, NaOH and CTMABr were very efficient in inducing a high zeta potential for titania in 50% EG. NaOH induced a negative zeta potential in excess of 70 mV, and HCl and CTMABr induced a positive zeta potential in excess of 70 mV at concentrations below 10⁻⁴ M. Apparently, HCl, NaOH and CTMABr are also more efficient than SDS in terms of nanofluid stabilization against coagulation. An overdose of base (>1 mM) results in depression of the negative zeta potential. This result may be due to the specific adsorption of sodium on titania from 50% EG.     

Production of Cellulase from Kraft Paper Mill Sludge by Trichoderma Reesei Rut C-30

Paper mill sludge is a solid waste material generated from pulping and papermaking operations. Because of high glucan content and its well-dispersed structure, paper mill sludges are well suited for bioconversion into value-added products. It also has high ash content originated from inorganic additives used in papermaking, which causes hindrance to bioconversion. In this study, paper mill sludges from Kraft process were de-ashed by a centrifugal cleaner and successive treatment by sulfuric acid and sodium hydroxide, and used as a substrate for cellulase production. The treated sludge was the only carbon source for cellulase production, and predominantly inorganic nutrients were used as the nitrogen source for this bioprocess. The cellulase enzyme produced from the de-ashed sludge exhibited cellulase activity of 8 filter paper unit (FPU)/mL, close to that obtainable from pure cellulosic substrates. The yield of cellulase enzyme was 307 FPU/g glucan of de-ashed sludge. Specific activity was 8.0 FPU/mg protein. In activity tests conducted against the corn stover and α-cellulose, the xylanse activity was found to be higher than that of a commercial cellulase. Relatively high xylan content in the sludge appears to have induced high xylanase production. Simultaneous saccharification and fermentation (SSF) was performed using partially de-ashed sludge as the feedstock for ethanol production using Sacharomyces cerevisiae and the cellulase produced in-house from the sludge. With 6% (w/v) glucan feed, ethanol yield of 72% of theoretical maximum and 24.4 g/L ethanol concentration were achieved. These results were identical to those of the SSF using commercial cellulases.     

Relative stability of selenites and selenates in feed premixes as a function of water activity

Sodium selenite is more hygroscopic than sodium selenate. It is, therefore, more likely to dissolve when dispersed in feeds of relatively high water activity. When dissolved, it may form selenious acid and disperse as a vapor. This is easily demonstrated by mounting a filter paper wetted with a reagent such as ascorbic acid over the subject feed, but not in contact with it. The paper turns brown as elemental selenium is formed from reduction of the vapor. Analysis of the paper ensures that the brown is indeed selenium. Though premixes are generally low enough in moisture content to ensure stability of the selenites, this is not true of many feeds. The water activities of a number of feeds, feed premixes, and feed ingredients have been determined instrumentally and compared to those of saturated solutions of sodium selenite and sodium selenate. There is no question that the selenite often dissolves with the potential to react and, in so doing, loses its nutritional function.     

Gas chromatographic method for the determination of selenite and total selenium in sea water

A method is described for the determination of dissolved selenite and total selenium in natural waters. The detection limit is approximately 10 pmol l^-1 and the reproducibility ±2.4% (1σ) at 394 pmol l^-1. A 100-ml sample containing selenite is reacted with 4-nitro-o-phenylenediamine to form 5-nitropiazselenol which is extracted into toluene and then determined by gas chromatography with an electron-capture detector. Other forms of selenium can be determined after photo-oxidizing samples under controlled pH conditions. This leads to a reproducible proportionation of species between selenite and selenate. The method has been used successfully to analyze samples both at sea and in the laboratory.     

Selenopheno[3,2-c]- and [2,3-c]coumarins: Synthesis,cytotoxicity, angiogenesis inhibition,and antioxidant properties

A simple method for the synthesis of substituted selenopheno[2,3-c] and -[3,2-c]coumarins by treatment of the corresponding ethynylcoumarins with in situ prepared selenium(IV) bromide in 1,4-dioxane-water was elaborated. Molecular structures for selected derivatives were confirmed by X-ray diffraction measurements. The cytotoxic activity of novel selenophenocoumarins showed higher activity and lower acute toxicity than sodium selenite on various tumor cell lines as well as an ability for inhibiting matrix metalloproteinases (MMP-1 – MMP-14), angiogenesis on matrigel in vitro and in vivo. The compounds exhibit antioxidant and prooxidant properties.     

Thermophilic Bacillus coagulans Requires Less Cellulases for Simultaneous Saccharification and Fermentation of Cellulose to Products than Mesophilic Microbial Biocatalysts

Ethanol production from lignocellulosic biomass depends on simultaneous saccharification of cellulose to glucose by fungal cellulases and fermentation of glucose to ethanol by microbial biocatalysts (SSF). The cost of cellulase enzymes represents a significant challenge for the commercial conversion of lignocellulosic biomass into renewable chemicals such as ethanol and monomers for plastics. The cellulase concentration for optimum SSF of crystalline cellulose with fungal enzymes and a moderate thermophile, Bacillus coagulans, was determined to be about 7.5 FPU g^?1 cellulose. This is about three times lower than the amount of cellulase required for SSF with Saccharomyces cerevisiae, Zymomonas mobilis, or Lactococcus lactis subsp. lactis whose growth and fermentation temperature optimum is significantly lower than that of the fungal cellulase activity. In addition, B. coagulans also converted about 80% of the theoretical yield of products from 40 g/L of crystalline cellulose in about 48 h of SSF with 10 FPU g^?1 cellulose while yeast, during the same period, only produced about 50% of the highest yield produced at end of 7 days of SSF. These results show that a match in the temperature optima for cellulase activity and fermentation is essential for decreasing the cost of cellulase in cellulosic ethanol production.