Synthesis of poly(hydroxamic acid) ligand from polymer grafted khaya cellulose for transition metals extraction

A cellulose-graft-poly(methyl acrylate) was synthesized by free radical initiating process and the ester functional groups were converted into the hydroxamic acid ligand. The intermediate and final products are characterized by FT-IR, FE-SEM, HR-TEM and XPS technique. The pH of the solution acts as a key factor in achieving optical color signals of metalcomplexation. The reflectance spectra of the [Cu-ligand]n+ complex was found to be a highest absorbance at 99.8 % at pH 6 and it was increased upon increasing of Cu²⁺ ion concentrations and a broad peak at 700 nm was observed which indicated the charge transfer (π-π transition) metals-Cu complex. The adsorption capacity of copper was found to be superior (336 mg g^?1) rather than other transition metals such as Fe³⁺, Co³⁺, Cr³⁺, Ni²⁺, Mn²⁺ and Zn²⁺ were 310, 295, 288, 250, 248 and 225 mg g^-1, respectively at pH 6. The experimental data of all metal ions fitted significantly with the pseudo-second-order rate equation. The transition metal ions sorption onto ligand were well fitted with the Langmuir isotherm model (R²>0.99), which suggested that the cellulose-based adsorbent known as poly(hydroxamic acid) ligand surface is homogenous and monolayer. The reusability of the poly(hydroxamic acid) ligand was checked by the sorption/desorption process up to ten cycles without any significant loss in its original sensing and removal performances.     

New fluorescent dye chemosensor for mercury ion (Hg2+) detection

The dye chemosensor for mercury ion detection was designed, which was based on donor-acceptor intramolecular charge transfer system and the corresponding fluorescence changing property was successfully monitored. This new dye chemosensor was containing dimethylcarbamodithioate groups to coordinate Hg²⁺, which showed very effective sensing functions. But it showed no significant changes upon the addition of other metal ions such as Ca²⁺, Pb²⁺, Al³⁺, Ce²⁺, Ba²⁺, Ni²⁺, Cd²⁺, Zn²⁺, and Mg²⁺.     

Ionochromism of Crystal Violet Lactone triggered by metal cations

The ionochromic properties of Crystal Violet Lactone(CVL), 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalate with metal cations were investigated. It showed interestingly ring open reaction with addition of several metal ions in CH₃CN solution. Upon addition of Hg²⁺, the CVL shows a new peak around 603nm in its absorption spectra, and the color of solution changed from colorless to blue. Whereas other ions including Fe³⁺, Cu²⁺, Fe²⁺, Al³⁺ and so on induced basically weakly spectral change, which makes it promising application in Hg²⁺ sensor.     

Benzothiazole-based semisquaraine as colorimetric chemosensor for Hg2+

A highly selective colorimetric chemosensor for Hg²⁺ based on the semisquaraine (BSQ) containing benzothiazole moiety was investigated. BSQ showed color change only with Hg²⁺, but it showed no significant changes upon addition of other metal ions such as Ca²⁺, Pb²⁺, Al³⁺, Ce²⁺, Ba²⁺, Ni²⁺, Cd²⁺, Zn²⁺, and Mg²⁺. Hg²⁺ ions coordinated to the BSQ forming 1:1 complex. The experimental data and conclusions are rationalized by DMol³ calculation results.     

Detector for rapid detection of trace Cu<Superscript>2+</Superscript> in paddy water based on dual-wavelength quantum dot fluorescent probe

A novel device is designed for rapid detection of trace Cu²⁺ residues in paddy water using dual-wavelength quantum dot fluorescence probe. It includes three operation procedures: synthesis of dual-wavelength quantum dot, fluorescence excitation and acquisition of weak signal and signal conditioning. Based on the quenching principle of Cu²⁺ on quantum dot fluorescence, dual-wavelength quantum dot fluorescent probe can get lower limitation of detection. In addition, to improve the accuracy of testing results, two-channel detection was developed for avoiding interference. Experiment results demonstrate that the limitation for detection of trace Cu²⁺ in paddy water is 1.4 nM. The relationship between the Cu²⁺ concentration (x) and the ratio variation of dual wavelength (y) is y?=?2.15?×?exp(x/5.862)???1.154 with the coefficient of determination (R²) of 0.997 and the detection time of 4 min. Meanwhile, compared to other heavy metal ions, nutrient and organic compounds, the presented detector is of good selectivity for Cu²⁺ in paddy water. The repetitive detection experiments show that the developed device has high repeatability with relative standard deviation of 0.14%. The device can be used for quick and accurate detection of trace Cu²⁺ residues in paddy water with some specific advantages of high sensitivity, excellent selectivity and high repeatability.     

Mineral binding capacity of dephytinized insoluble fiber from extruded wheat,oat and rice brans

Insoluble fiber fractions from raw and extruded oat, rice and wheat brans were isolated and phytate removed. In vitro mineral binding studies were performed utilizing copper (Cu²⁺), calcium (Ca²⁺) and zinc (Zn²⁺) ions, which were added individually to enzymatically treated (Prosky et al., 1985), acid washed insoluble fiber residues from oat, rice and wheat brans. The enzymatic digestion step with alpha-amylase, protease and amyloglucosidase served to remove protein and starch from the samples. Mineral binding studies were performed on the insoluble fiber residue. Mineral content was determined by flame atomic absorption spectroscopy. Raw brans served as controls. A twin-screw extruder Model DNDG-62/20D, manufactured by Bühlerag (CH-9240, Uzwil, Switzerland) was utilized. The objectives of the study were to determine the total Cu²⁺, Ca²⁺ and Zn²⁺binding capacity of the dephytinized insoluble fiber from each bran; and to determine if extrusion screw speed affected the brans' insoluble fiber mineral binding capacity. Although dephytinized, the brans' insoluble fiber fraction bound Cu²⁺, Ca²⁺ and Zn²⁺ions. Oat bran bound more Cu²⁺, Ca²⁺ and Zn²⁺ than wheat bran, which bound more than rice bran. Extrusion processing did not affect the brans' insoluble fiber binding capacity to bind Cu²⁺. However, it increased the binding capacity of Ca²⁺ and Zn²⁺ of the insoluble fiber fraction from rice and oat brans.     

Purification and Characterization of a Novel Alginate Lyase from a Marine Streptomyces Species Isolated from Seaweed

Alginate, a natural polysaccharide derived from brown seaweed, is finding multiple applications in biomedicine via its transformation through chemical, physical, and, increasingly, enzymatic processes. In this study a novel alginate lyase, AlyDS44, was purified and characterized from a marine actinobacterium, Streptomyces luridiscabiei, which was isolated from decomposing seaweed. The purified enzyme had a specific activity of 108.6 U/mg, with a molecular weight of 28.6 kDa, and was composed of 260 amino acid residues. AlyDS44 is a bifunctional alginate lyase, active on both polyguluronate and polymannuronate, though it preferentially degrades polyguluronate. The optimal pH of this enzyme is 8.5 and the optimal temperature is 45 °C. It is a salt-tolerant alginate lyase with an optimal activity at 0.6 M NaCl. Metal ions Mn²⁺, Co²⁺, and Fe²⁺ increased the alginate degrading activity, but it was inhibited in the presence of Zn²⁺ and Cu²⁺. The highly conserved regions of its amino acid sequences indicated that AlyDS44 belongs to the polysaccharide lyase family 7. The main breakdown products of the enzyme on alginate were disaccharides, trisaccharides, and tetrasaccharides, which demonstrated that this enzyme acted as an endo-type alginate lyase. AlyDS44 is a novel enzyme, with the potential for efficient production of alginate oligosaccharides with low degrees of polymerization.     

Effects of crude oil spillage on growth and yield of maize (Zea mays L.) in soils of midwestern Nigeria

The effect of crude oil spillage on growth, productivity and nutrient uptake of maize (Zea mays L.) was assessed in a pot experiment using an Evwreni manifold sample of a petroleum development company, which had aspecific gravity of 0.8778. The Suwan 1 variety of maize was used in the experiment. In crude oil polluted soils, germination was delayed and the germination percentage was significantly affected by oil pollution. Growth was poor in polluted soils using parameters such as plant height, stem girth,ear height, leaf area at four weeks after planting, leaf area at maturity and average length of primary roots as growth indicators. Grain yield was significantly reduced at 95% level of probability with yield (when compared with the control) reduced by as much as 98.6%, 96.5% and 58.3% for preplant,five weeks after planting (5 WAP) and seven weeks after planting (7 WAP) treatments, respectively. Leaf analysis of the maize plants grown in soilscontaminated with crude oil a week before planting (preplant treatment) revealed mean levels of heavy metals (6.18 ppm Zn²⁺, 0.62 ppm Cu²⁺,26.24 ppm Fe²⁺, 10.84 ppm Mn²⁺, 2.96 ppm Pb²⁺ and 3.88 ppm Co²⁺) which are higher than the maximum permissible levels (MPL) for maize in tropical soils. Maize plants that were polluted at other time intervals showed no significant (p>0.05) variation in heavy metal concentrations when compared with the control, and were considered potentiallysafe for human consumption.     

Preparation of electrospun silk fibroin/Cellulose Acetate blend nanofibers and their applications to heavy metal ions adsorption

Silk fibroin (SF)/Cellulose Acetate (CA) blend nanofibrous membranes were prepared by electrospinning and their heavy metal absorbabilities were examined in an aqueous solution after ethanol treatment. The electrospun nanofibrous membranes were comprised of randomly oriented ultrafine fibers of 100–600 nm diameters. As a result of field emission electron microscope (FEEM), the anti-felting properties of the blend nanofibrous membranes were markedly improved after treatment with 100 % ethanol when SF was blended with CA. Metal ion adsorption test was performed with Cu²⁺ as a model heavy metal ion in a stock solution. The SF/CA blend nanofiber membranes showed higher affinity for Cu²⁺ in an aqueous solution than pure SF and pure CA nanofiber membranes. Especially, the blend nanofibrous membranes with 20 % content of CA had an exceptional performance for the adsorption of Cu²⁺, and the maximum milligrams per gram of Cu²⁺ adsorbed reached 22.8 mg/g. This indicated that SF and CA had synergetic effect. Furthermore, the parameters affecting the metal ions adsorption, such as running time and initial concentration of Cu²⁺, had been investigated. The results showed that the adsorption of the Cu²⁺ sharply increased during the first 60 min, the amount of metal ions adsorbed increased rapidly as the initial concentration increased and then slope of the increase decreased as the concentration further increased. This study provides the relatively comprehensive data for the SF/CA blend nanofibrous membranes application to the removal of heavy metal ion in wastewater.     

Molecular mapping of quantitative trait loci for zinc toxicity tolerance in rice seedling (Oryza sativa L.)

Excess zinc harms the growth of rice plants and zinc toxicity can easily occur in acid soils. The aim of the study was to map quantitative trait loci (QTLs) in rice for tolerance to zinc toxicity, using a recombinant inbred (RI) population derived from the cross of a japonica variety (Asominori: relatively tolerant to Zn²⁺ toxicity) with an indica variety (IR24, relatively susceptible), through 289 RFLP markers. The index scores of damage (representing Zn²⁺ toxicity tolerance), after irrigating rice seedlings with a 1000-ppm Zn²⁺ solution for 20 successive days, were examined for each RI line and its parental varieties. Continuous distributions and transgressive segregations of the index scores were observed in the RI population, suggesting that Zn²⁺ toxicity tolerance was a quantitatively inherited trait. Three QTLs for Zn²⁺ toxicity tolerance were detected on chromosomes 1, 3 and 10 and explained 21.9, 8.9 and 7.6%, respectively, of the total phenotypic variation. The results and the tightly linked molecular markers that flank the QTLs, detected in this study, will be useful in improving Zn²⁺ tolerance in rice. In addition, the genomic positions between QTLs for Zn²⁺ toxicity tolerance and the QTLs for other metal (Fe²⁺, Mn²⁺, Al³⁺) toxicity tolerances, from previous studies, are discussed.     

Evaluation of a Thermophilic,Psychrostable, and Heavy Metal-Resistant Red Sea Brine Pool Esterase

Lipolytic enzymes catalyze the hydrolysis and synthesis of ester compounds. They are valuable in the pulp, food, and textile industries. This study aims to comprehensively evaluate the extreme properties of a hormone-sensitive lipase (EstATII-TM) isolated from the Red Sea Atlantis II brine pool. EstATII-TM was cloned, expressed, and its biochemical activities were assessed under different conditions. EstATII-TM catalytic properties and resistance to different metal ions were compared to commercial thermophilic esterases under different temperatures. Phylogenetically, EstATII-TM was assigned to the GDSAG motif subfamily of hormone-sensitive lipase. The optimal enzyme activity was evident at a temperature of 30 °C and pH 7–8. The enzyme retained 84.9% of its activity at 0.5 M NaCl. EstATII-TM maintained 93% to 97% activity at −40 and −20 °C, respectively. EstATII-TM activity was significantly enhanced, up to 10-fold, at temperatures ranging from 45 to 65 °C in the presence of 1 mM Cu²⁺, Cd²⁺, Ba²⁺, Mn²⁺, and Zn²⁺. EstATII-TM showed superior catalytic activity and resistance-to/enhancement-by metal ions compared to two commercial thermophilic esterases. The Red Sea Atlantis II brine EstATII-TM is characterized by tolerance to high temperatures, stability to hot and cold conditions, as well as toxic heavy metal contamination, making it an ideal candidate for industrial processes.     

A novel heterogeneous Fenton photocatalyst prepared using waste wool fiber combined with Fe<Superscript>3+</Superscript> ions for dye degradation

Wool fiber Fe complex (Fe-Wool) was prepared with waste wool fiber and Fe³⁺ ions by a simple exhaust method, and characterized using SEM, FTIR, XRD, XPS, and diffuse reflectance UV-vis spectroscopy. The activity of Fe-Wool was tested as a novel heterogeneous Fenton catalyst for dye degradation in a wide pH range. Effect of Fe content, incorporation of Cu²⁺ ions, and light irradiation on its catalytic activity was also examined. The results indicated that amino and carboxylic groups or disulfide crosslinks from wool fiber as the ligand sites could react with Fe³⁺ ions to form Fe-Wool, and the Fe content in Fe-Wool was highly dependent on Fe³⁺ initial concentration and temperature. Fe-Wool showed a better catalytic activity on the dye degradation under light irradiation than in the dark because it was activated in the UV and visible regions. Incorporation of Cu²⁺ ions could significantly increase catalytic activity of Fe-Wool for the dye degradation, especially in neutral and alkaline pH range.     

Cloning and Characterization of a Novel Endo-Type Metal-Independent Alginate Lyase from the Marine Bacteria Vibrio sp. Ni1

The applications of alginate lyase are diverse, but efficient commercial enzymes are still unavailable. In this study, a novel alginate lyase with high activity was obtained from the marine bacteria Vibrio sp. Ni1. The ORF of the algB gene has 1824 bp, encoding 607 amino acids. Homology analysis shows that AlgB belongs to the PL7 family. There are two catalytic domains with the typical region of QIH found in AlgB. The purified recombinant enzyme of AlgB shows highest activity at 35 °C, pH 8.0, and 50 mmol/L Tris-HCl without any metal ions. Only K⁺ slightly enhances the activity, while Fe²⁺ and Cu²⁺ strongly inhibit the activity. The AlgB preferred polyM as substrate. The end products of enzymatic mixture are DP2 and DP3, without any metal ion to assist them. This enzyme has good industrial application prospects.     

An efficient,simple and facile strategy to synthesize Polypropylene-g-(acrylic acid-co-acrylamide) nonwovens by suspension grafting polymerization and melt-blown technique

An efficient, simple and facile process, i.e., suspension grafting polymerization combined with melt-blown technique, was employed to synthesize Polypropylene-g-(acrylic acid-co-acrylamide) nonwoven fabrics [PP-g-(AA-co-AM) nonwovens]. In this study, the grafting mechanism and the effect of synthesis parameters on grafting percentage (GP) were investigated. The as-synthesized products were characterized by melt flow rate (MFR), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), water contact angle (WCA) and thermalgravimetric analysis (TGA). Besides, the uptake properties of metal ions (i.e., Ba²⁺, Cu²⁺, Ni²⁺, Mg²⁺, Al3+, Ca²⁺) on the PP-g-(AA-co-AM) nonwovens in dynamic condition were studied. Results of FTIR showed that AA and AM were successfully grafted onto the PP surface. The decrease in WCAs of the grafted nonwovens with the increasing GP indicated that (AA-co-AM) side chains existed as the hydrophilic component. TGA results revealed that no significant change in thermal stability was found in grafted PP samples. The synthesis experiments showed that the highest GP was obtained at grafting time 3 h, water 3 ml/g, xylene 15 wt%, benzoyl peroxide 0.5 wt%, AA, AM 30 wt% and AA: AM 1:1, with a GP of 16.7 %, and a grafting efficiency of 67 %. However, MFR measurement and SEM image demonstrated that PP-g-(AA-co-AM) nonwovens with the highest GP showed almost no mechanical strength existed between filaments resulting in the occurrence of deformation and contraction of nonwovens, and breaking up into small pieces. Comprehensively, the optimal GP was 8.7 %, and the corresponding PP-g-(AA-co-AM) nonwovens exhibited higher metal ions uptake capacity than pristine PP nonwovens in the dynamic adsorption process.     

Electrical Resistivity of Plasma Treated Viscose and Cotton Fabrics with Incorporated Metal Ions

Cellulose fabrics (viscose and cotton) were treated with atmospheric pressure dielectric barrier discharge (DBD) in air. After DBD treatment, samples were characterized and volume electrical resistance was measured under different relative humidity conditions (φ=40-55 %). Results have shown that DBD treatment increases wettability and polar surface functional groups content, which consequently causes a decrease of volume electrical resistivity of cellulose fabrics in measured relative humidity range (φ=40-55 %). Metal ions (silver, copper, and zinc) were incorporated in untreated and plasma treated samples through sorption from aqueous solutions and incorporation of metal ions into plasma treated cellulose samples decreased electrical resistivity even further. Resistivity of cotton and viscose fabrics with incorporated metal ions followed the order Zn²⁺ > Cu²⁺ > Ag⁺. The most pronounced decrease, for entire order of a magnitude, was obtained by modification of cotton fabric with DBD and silver ions, where value of resistivity dropped from GΩ to a several dozens of MΩ.     

Surface modified ployacrylonitrile nanofibers and application for metal ions chelation

Ployacrylonitrile (PAN) nanofibers were formed by electrospinning. Amidoxime ployacrylonitrile (AOPAN) nanofibers were prepared by reaction with hydroxylamine hydrochloride, which were used as the matrix for metal ions chelation. FTIR spectra of the PAN nanofibers and AOPAN nanofibers were recorded for analysis of the surface chemical structures. The AOPAN conventional fibers were also prepared for comparison, and surface morphologies of the modified PAN conventional fibers and PAN nanofibers were observed by FESEM. Metal ions concentrations were calculated by AAS. The chelated isothermal process and kinetics parameters of the modified PAN nanofibers and PAN conventional fibers were studied in this work. Results indicated that the saturated coordinate capacity of AOPAN nanofibers to Cu²⁺, Cd²⁺ was 3.4482 and 4.5408 mmol/g (dry fiber) respectively, nearly two times higher than that of AOPAN conventional fibers. Besides, the desorption rate of Cu²⁺ and Cd²⁺ from metal chelated AOPAN nanofibers was 87 and 92 % respectively in 1 mol/l nitric acid solution for 60 min. The isothermal processes were found to be in conformity with Langmuir model.     

Metal adsorption of tannin based rigid foams

Tannin based rigid foams are structures in which flavonoids are randomly cross-linked with furanic units throughout covalent bonds. The use of these aromatic substrates from natural materials to trap some heavy metal ions dissolved in water solutions is described. Interesting results have been achieved using different mimosa bark tannin (Acacia mearnsii formerly mollissima, De Wildt) and pine bark tannin (Pinus radiata) mixed foams. Capability to catch Pb²⁺ and Cu²⁺ ions at different concentrations has been verified throughout ICP-OES analysis of the foams. A reliable proportionality has been found between initial concentration and percentage of metal ions adsorbed. These foams were able to adsorb up to 12.5% of Cu(II) and 20.1% of Pb(II) with respect to the concentration of these ions in solution.     

Effect of additives on flavonoids, d-chiro-Inositol and trypsin inhibitor during the germination of tartary buckwheat seeds

In this study, we evaluated tartary buckwheat during germination to provide an effective process that can lead to a rapid accumulation of both the total flavonoids and d-chiro-Inositol (DCI), as well as the elimination of trypsin inhibitor activity. At different concentrations of Al³⁺, Cu²⁺, and Zn²⁺, we found significant differences of the total flavonoids and DCI accumulation, and we observed changes in phenylalanine ammonia-lyase (PAL), chalcone isomerase (CHI), and α-Galactosidase (α-Gal) activities in germinated tartary buckwheat (p < 0.05). Correlation analysis between these enzymes (PAL, CHI and α-Gal) activities and the total flavonoids and DCI contents revealed a significant correlation in germinated tartary buckwheat. The maximum accumulation of the total flavonoids and DCI were 1315.52 mg/100 g DW and 60.46 mg/g DW with the addition of Al³⁺, 1315.41 and 63.59 with the addition of Cu²⁺, and 1189.42 and 53.10 with the addition of Zn²⁺. In these metal-treated samples, both total flavonoids and DCI were significantly higher than in the control (p < 0.05). Moreover, the metallic additives at the optimum concentration had no influence on total protein content, whereas a lower trypsin inhibitor activity was observed in correlation with higher protein digestibility.     

Cadmium-Containing Carbonic Anhydrase CDCA1 in Marine Diatom Thalassiosira weissflogii

The Carbon Concentration Mechanism (CCM) allows phytoplakton species to accumulate the dissolved inorganic carbon (DIC) necessary for an efficient photosynthesis even under carbon dioxide limitation. In this mechanism of primary importance for diatoms, a key role is played by carbonic anhydrase (CA) enzymes which catalyze the reversible hydration of CO₂, thus taking part in the acquisition of inorganic carbon for photosynthesis. A novel CA, named CDCA1, has been recently discovered in the marine diatom Thalassiosira weissflogii. CDCA1 is a cambialistic enzyme since it naturally uses Cd²⁺ as catalytic metal ion, but if necessary can spontaneously exchange Cd²⁺ to Zn²⁺. Here, the biochemical and structural features of CDCA1 enzyme will be presented together with its putative biotechnological applications for the detection of metal ions in seawaters.     

Heated Leaf Extract of Coriandrum sativum L. Protects Nigral Dopaminergic Degeneration in Rats

Coriandrum sativum L. (coriander), which is an annual herb of the Apiaceae family, has been traditionally used as a remedy. Here we tested whether heated extract of coriander leaf protects nigral dopaminergic neurodegeneration after exposure to 6-hydroxydopamine (6-OHDA). After injection of 6-OHDA into the rat substantia nigra pars compacta (SNpc), dopaminergic degeneration, which was determined by tyrosine hydroxylase immunostaining, was rescued by co-injection of CaEDTA, an extracellular Zn²⁺ chelator, suggesting that extracellular Zn²⁺ influx is involved in neurodegeneration. Both intracellular Zn²⁺ dysregulation determined by ZnAF-2 fluorescence and dopaminergic degeneration in the SNpc induced by 6-OHDA were rescued by co-injection of 0.25% coriander extract, which also reduced reactive oxygen species (ROS) production in the SNpc determined by aminophenyl fluorescein fluorescence. The present study suggests that coriander leaf extract protects nigral dopaminergic neurodegeneration induced by intracellular Zn²⁺ dysregulation. It is likely that the nutraceutical property of coriander leaf extract contributes to the protection via reducing ROS production.