Active Metal Ions Research Articles

Alkaline serine protease from the new halotolerant alkaliphilic Salipaludibacillus agaradhaerens strain AK-R: purification and properties.

Herein, we report the purification and characterization of an alkaline protease from the alkaliphilic Salipaludibacillus agaradhaerens (formerly Bacillus agaradhaerens) strain AK-R, which was previously isolated from Egyptian soda lakes. The purification procedures resulted in enzyme purification up to 13.3-fold, with a recovery yield of 16.3% and a specific activity of 3488 U/mg protein. AK-R protease was a monomeric protein with an estimated molecular weight of 33.0kDa. The optimum pH and temperature for AK-R protease were pH 10 and 60°C, respectively. The enzyme thermostability was significantly enhanced in the presence of CaCl2 by approximately 1.3-fold. Moreover, under optimal conditions, the K m and V max values of the enzyme were 2.63mg/ml and 4166.7 U/mg, respectively. PMSF caused complete inhibition of the enzyme activity, suggesting that AK-R belongs to the serine protease family. In addition, the enzyme was completely inhibited by EDTA, revealing the requirement of metal ions for AK-R protease activity; hence, it can be classified as a metalloprotease. AK-R protease is a mostly thiol-independent enzyme, since thiol reductants such as β-mercaptoethanol and dithiothreitol had no effect on the enzyme activity. AK-R protease exhibited high stability in several organic solvents, including butanol, amyl alcohol, dimethyl ether, toluene, diethyl ether and methanol. Moreover, AK-R protease showed significant stability to a variety of surfactants and commercial detergents. The features and properties of AK-R alkaline protease are favourable and suggest its potential applications in various industries, particularly in the laundry detergent industry.

Simultaneous studies on kinetics, bio-adsorption behaviour of chitosan grafted thin film nanohydrogel for removal of hazardous metal ion from water

Natural biodegradable chitosan (CS) based thin film nanogels (TNG)s were developed and optimized in order to obtain films possessing the optimal functional properties (biodegradabiity, nontoxicity and bioadhesion) to be applied for heavy metal ion removal from aqueous systems. The grafting of 2-hydroxyethyl methacrylate (HEMA) and acrylic acid (AA) onto CS via redox initiator system of ammonium persulfate (APS) and complex catalyst CuSO4/glycine (1:1) in the presence of foaming agent sorbitol was designed. The CS-g-P(HEMA-co-AA)/nano-CaO, a novel thin film was prepared from the combination of CS-g-P (HEMA-co-AA) copolymers with the modified snail shell, nano-CaO as a nanofiller, then the so prepared CS-g-P(HEMA-co-AA)/nano-CaO nanogel thin film is used to encapsulate active toxic heavy metal ions in water systems. Characterization of TNGs was done by FT-IR, XRD, TGA, FESEM. In addition, their kinetic isotherms with proper kinetic model at optimum pH were studied. The Langmuir and the Langmuir-Freundlich adsorption isotherm models obtained by the UV spectrophotometer were applied to describe the isotherm parameter for Cr (VI) adsorption by TNG. So the TNGs are potentially suitable for use as superadsorbents exhibiting good biodegradability and are cost-effective for their better commercialization and industrialization as well.

Temporal and Spatial Variations in the Conductivity in Different Media in Taihu Lake, China

Conductivity is an important parameter for characterizing dissolved solids and salinity in water, and is also one of the routinely measured parameters in water quality monitoring. To reveal temporal and spatial variations in conductivity in different media in Taihu Lake, historical data (1980-2009) were collected and field monitoring data (2009-2018) were analyzed. The results indicated that water conductivity in Taihu Lake has shown a significant increasing trend over the past 40 years and diverged in 1996-1997. Conductivity values increased from (239.43±70.60)μS·cm-1 in the period 1980-1996 to(477.31±23.47)μS·cm-1 in the present day, with an average annual increase of 10.40 μS·(cm·a)-1. Spatially, the conductivity of water in the northwest part of the lake was significantly higher than the southeast part. These changes in conductivity are dominated by changes in major ions, and the contribution of nitrogen was essentially negligible. Human activities in the basin have been the main factors causing changes in water conductivity. In addition, conductivity is significantly affected by seasonal runoff. Compared with the water, the conductivity of the surface sediments and pore water (0-10 cm) in the northwest part of the lake were lower than in the southeast part, while this trend was opposite in the deeper sediments (>10 cm). The conductivity of the sediment and pore water were no different between surface (0-10 cm) and deeper (>10 cm) sediments in the northwest lake, while these were higher in the surface sediments in the southeast part of the lake. Sediment conductivity was positively correlated with organic matter (P<0.01) and was negatively correlated with pH (P<0.05). This indicated that organic matter promotes the activation and migration of metal ions, which are more activated under acidic conditions. We found that conductivity in the surface sediments and pore water (0-10 cm) were significantly positively correlated with conductivity in the overlying water (P<0.01). In contrast, the conductivity of overlying water was not correlated with the conductivity of deeper sediments and pore water (>10 cm). These patterns indicated that surface sediments and pore water have a significant effect on the conductivity of overlying waters. In addition, there was a significant positive correlation between the conductivity of sediment and pore water (P<0.01) within the entire sedimentary section (0-50 cm), indicating efficiency ion-exchange between the two. The interaction between sediment and pore water was generally stronger than their interaction with the overlying water.

Selective metal ions doped CeO2 nanoparticles for excellent photocatalytic activity under sun light and supercapacitor application

Herein, photocatalytic activity of pure CeO2 and different metal ions (Ag, Bi, Cd and Pb) doped CeO2 nanoparticles (NPs) is investigated using degradation of methylene blue (MB) dye under direct sunlight irradiation. In addition, electrochemical supercapacitor was performed for selected metal ion doped CeO2 NPs. All the NPs are synthesized by one-step chemical precipitation method in aqueous medium at room temperature. The prepared samples were characterized by XRD, FE-SEM, TEM, FT-IR, Laser Raman, UV–Vis, PL, EPR, TGA and electrochemical techniques. According to XRD analysis, the synthesized pure CeO2 and doped CeO2 NPs are cubic crystal structure. Among the dopants, Ag doped CeO2 exhibited excellent photocatalytic activity by degrading of more than 99.5% of the MB dye within 120 min irradiation under sunlight. The enhanced photocatalytic activity of doped CeO2 NPs was ascribed to the significant suppression of the recombination rate of photo-generated electron–hole pairs due to charge transfer, increasing oxygen vacancy and the smaller optical band-gap. The reason behind the photocatalytic activity enhancement is studied through photoluminescence (PL) and the results indicated that the emission peak intensity of pure CeO2 decreased compared to the doped CeO2. The PL quenching was associated with a decrease in the electron–hole recombination rate. Electrochemical supercapacitor was performed for the best photocatalyst of Ag doped CeO2 NPs, the result found to be specific capacitance of 456 F g−1 at 3 A g−1 current density. Among the different metal ions, the Ag doped CeO2 showed as an excellent catalyst for dye degradation and electrochemical supercapacitor applications.

Substrate-to-Product Conversion Facilitates Active Site Loop Opening in Yeast Enolase: A Molecular Dynamics Study.

Yeast enolase serves as a prototype for metalloenzymes with labile, catalytic active site metal ions and is important for glycolysis and fermentation processes. Herein, microsecond molecular dynamics simulations of the protein-substrate and protein-product complexes are conducted to elucidate the mechanism of the opening of catalytically important active site loops. These simulations indicate that conversion of substrate to product is accompanied by diminished metal coordination and hydrogen-bonding interactions, as well as enhanced loop flexibility. Moreover, free energy simulations show that the loop opening is endergonic when substrate is bound but exergonic when product is bound. Thus, the conversion to product weakens the association of the loop with the ligand and binding site, thereby facilitating the loop opening after catalysis and enabling product release. These insights about active site loop motions in enzyme catalysis may be useful in guiding enzyme design efforts.

A Perspective on Recent Advances in Piezoelectric Chemical Sensors for Environmental Monitoring and Foodstuffs Analysis

This paper provides a selection of the last two decades publications on the development and application of chemical sensors based on piezoelectric quartz resonators for a wide range of analytical tasks. Most of the attention is devoted to an analysis of gas and liquid media and to industrial processes controls utilizing single quartz crystal microbalance (QCM) sensors, bulk acoustic wave (BAW) sensors, and their arrays in e-nose systems. The unique opportunity to estimate several heavy metals in natural and wastewater samples from the output of a QCM sensor array highly sensitive to changes in metal ion activity in water vapor is shown. The high potential of QCM multisensor systems for fast and cost-effective water contamination assessments “in situ” without sample pretreatment is demonstrated.

MeLAD: an integrated resource for metalloenzyme-ligand associations.

Metalloenzymes are attractive targets for therapeutic intervention owing to their central roles in various biological processes and pathological situations. The fast-growing body of structural data on metalloenzyme-ligand interactions is facilitating efficient drug discovery targeting metalloenzymes. However, there remains a shortage of specific databases that can provide centralized, interconnected information exclusive to metalloenzyme-ligand associations. We created a Metalloenzyme-Ligand Association Database (MeLAD), which is designed to provide curated structural data and information exclusive to metalloenzyme-ligand interactions, and more uniquely, present expanded associations that are represented by metal-binding pharmacophores (MBPs), metalloenzyme structural similarity (MeSIM) and ligand chemical similarity (LigSIM). MeLAD currently contains 6086 structurally resolved interactions of 1416 metalloenzymes with 3564 ligands, of which classical metal-binding, non-classical metal-binding, non-metal-binding and metal water-bridging interactions account for 63.0%, 2.3%, 34.4% and 0.3%, respectively. A total of 263 monodentate, 191 bidentate and 15 tridentate MBP chemotypes were included in MeLAD, which are linked to different active site metal ions and coordination modes. 3726 and 52740 deductive metalloenzyme-ligand associations by MeSIM and LigSIM analyses, respectively, were included in MeLAD. An online server is provided for users to conduct metalloenzyme profiling prediction for small molecules of interest. MeLAD is searchable by multiple criteria, e.g. metalloenzyme name, ligand identifier, functional class, bioinorganic class, metal ion and metal-containing cofactor, which will serve as a valuable, integrative data source to foster metalloenzyme related research, particularly involved in drug discovery targeting metalloenzymes. MeLAD is accessible at https://melad.ddtmlab.org. Supplementary data are available at Bioinformatics online.

Structure of an α-glucuronidase in complex with Co2+ and citrate provides insights into the mechanism and substrate recognition in the family 4 glycosyl hydrolases

Glycosyl hydrolases belonging to the family 4 (GH4) use a unique redox-based NAD+-dependent reaction mechanism involving anionic intermediates and requires a divalent metal ion and reducing conditions for catalytic activity. These enzymes display wide specificity and selectivity for their substrates. However, the structural basis of substrate binding, recognition and specificity remains poorly studied. Here, we report the crystal structure of Thermotoga maritima TmAgu4B, a GH4 α-glucuronidase, in complex with Co2+ and citrate. Analysis of GH4 structures show that the metal ion is present in a conserved octahedral coordination with conserved side chain atoms, the ligand atoms and an invariant water molecule. The data provides the first structural evidence for a metal-activated hydroxide ion that acts as the general base to deprotonate the C3-hydroxyl group of the glycone, a rate-limiting step in the mechanism. Furthermore, the citrate binding mode in the active site is analogous to a bound glucuronide substrate and provides insights into the mode of substrate interaction with the metal ion, the active site residues and, the structural basis of substrate recognition in a GH4 α-glucuronidase.

Hydrangea‐like NiCo‐based Bimetal‐organic Frameworks, and their Pros and Cons as Supercapacitor Electrode Materials in Aqueous Electrolytes

Hydrangea‐like NiCo‐based bimetal‐organic frameworks (NiCo‐MOF) are synthesized in DMF‐EtOH solution via a solvothermal method, using 4,4′‐biphenyldicarboxylic acid as a ligand. NiCo‐MOF having a highest capacity of 1056.6 F·g–1 at 0.5 A·g–1 and 457.7 F·g–1 even at 10 A·g–1 is achieved at a Ni/Co/BPDC molar ratio of 1:1:1, a temperature of 170 °C and a reaction time of 12 hours. It exhibits secondary 3D microsphere structures assembled by primary 2D nanosheet structures, good crystalline structure and good thermal stability below 350 °C in air. All the electrochemical data show that NiCo‐MOF has the pros and cons as supercapacitor electrode materials in aqueous electrolytes. On the one hand, NiCo‐MOF has a high capacity even at a high current density, low internal resistance, charge‐transfer resistance and ion diffusion impendence, owing to the ordered coordination structure, 2D nanosheet structure and 3D assembled microsphere structure of NiCo‐MOF. On the other hand, the cycling stability and rate capability are not ideal enough due to the hydrolysis of coordination bonds in aqueous electrolytes, especially, in alkaline solution. The good dispersion and high electrochemical activity of metal ions bring a high capacity for NiCo‐MOF, but they result in the poor stability of NiCo‐MOF. In the future work, finding a suitable organic electrolyte is an effective way to enhance the cycling stability of NiCo‐MOF as well as deriving more stable skeleton materials from NiCo‐MOF.

The Effect of Extraction Methods on Preliminary Structural Properties and Antioxidant Activities of Polysaccharides from Lactarius vividus

Four polysaccharides (LVP-u, LVP-m, LVP-e, and LVP-h) were extracted from the fruiting bodies of Lactarius vividus by an ultrasonic-assisted extraction method, microwave-assisted extraction method, enzyme-assisted extraction method, and hot water extraction method, respectively. Then, the effect of extraction methods on yields, preliminary structural properties, and antioxidant activities was systematically investigated using the weighing method, chemical composition analysis, high-performance gel permeation chromatography (HPGPC), high-performance liquid chromatography (HPLC), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), radical scavenging, and metal ion chelating assays. Results demonstrated that the four L. vividus polysaccharides (LVPs) were all combined with protein, and the yield of LVP-u was higher than others. Molecular weight distribution, monosaccharide and amino acid compositions, and microstructures among the four LVPs were significantly different. Moreover, the LVPs showed significant antioxidant activities in a dose-dependent manner, and LVP-e demonstrated better antioxidant activities in superoxide anion radical scavenging activity assays and metal ion chelating activity assays, while LVP-u showed higher activity in its hydroxyl radical scavenging ability.

Corynebacterium diphtheriae: Diphtheria Toxin, the tox Operon, and Its Regulation by Fe2+ Activation of apo-DtxR.

Diphtheria is one of the most well studied of all the bacterial infectious diseases. These milestone studies of toxigenic Corynebacterium diphtheriae along with its primary virulence determinant, diphtheria toxin, have established the paradigm for the study of other related bacterial protein toxins. This review highlights those studies that have contributed to our current understanding of the structure-function relationships of diphtheria toxin, the molecular mechanism of its entry into the eukaryotic cell cytosol, the regulation of diphtheria tox expression by holo-DtxR, and the molecular basis of transition metal ion activation of apo-DtxR itself. These seminal studies have laid the foundation for the protein engineering of diphtheria toxin and the development of highly potent eukaryotic cell-surface receptor-targeted fusion protein toxins for the treatment of human diseases that range from T cell malignancies to steroid-resistant graft-versus-host disease to metastatic melanoma. This deeper scientific understanding of diphtheria toxin and the regulation of its expression have metamorphosed the third-most-potent bacterial toxin known into a life-saving targeted protein therapeutic, thereby at least partially fulfilling Paul Erlich's concept of a magic bullet-"a chemical that binds to and specifically kills microbes or tumor cells."

Spectroscopic and molecular docking elucidation to binding characteristics of bovine serum albumin with bupropion an aminoketone-medication for nicotine addiction

One of the highly soluble protein presents in circulatory system of bovine body is bovine serum albumin (BSA). Bupropion hydrochloride (BRN) served to treat prime smoking cessation and disorder due to depressive. BRN binding to BSA was studied by molecular docking and lots of spectroscopic (UV-vis, emission, synchronous, 3D fluorescence, CD and FT-IR) methods at pH = 7.40. Static quenching with strong binding was obtained for BSA-BRN system by forming complex. Secondary structures, conformations and microenvironments of BSA were altered after BRN interaction. Distance between BRN and BSA was also achieved. Biologically active metal ions (Cu2+, Ca2+, Mg2+, Fe2+ and Zn2+) were also influenced on the BSA-BRN complex. Bonds of hydrogen and Van der Waals were major binding forces to stabilize BSA-BRN complex at site I (IIA) of BSA. Hence, binding of BRN to transport protein (BSA) is of prominent importance and these findings could be helpful for BRN pharmacology and potential clinical research.

ВМІСТ ФЕРУМУ, МАНГАНУ, КОБАЛЬТУ, ЦИНКУ ТА КУПРУМУ В ОРГАНІЗМІ РИБ ІЗ РІЧОК СЕРЕТ, СТРИПА І ЗОЛОТА ЛИПА

The content of individual metals in carp, crucian carp, perch and pike tissues from small rivers of Western Podillya is investigated. It is shown, that for different metals there are individual patterns of accumulation in different tissues of the organism. However, the general tendencies that determine cellular transformations in fish are: tissue-specific cell localization, due to their morphology, chemical composition and membrane activity; chemical activity of metal ion, especially complexing ability with proteins and low molecular weight metabolites; concentration of ions, which affects the total ionic homeostasis in the organism. The maximum level of accumulation of the Mangan, Ferum and Copper in the tissues of fishes from Strypa, Cobalt, and Zinc in the tissues of fishes from Seret river is noted. In the Zolota Lypa river, in the vast majority of cases, accumulation of the minimum amount of metals in tissues of investigated species of fish took place, which may be due to the low bioavailability of metals for both predatory fish and benthophages.Pollution of internal reservoirs, including fishing, is one of the limiting factors for the functioning of aquatic ecosystems and their bioproductivity. The study of physiological and biochemical mechanisms of accumulation and distribution of metals in fish tissues under conditions of contamination of water ecosystems is one of the main conditions for the development of effective means of increasing the organism's resistance to new conditions of existence.

Enhancement of RNA/Ligand Association Kinetics via an Electrostatic Anchor.

The diverse biological processes mediated by RNA rest upon its recognition of various ligands, including small molecules and nucleic acids. Nevertheless, a recent literature survey suggests that RNA molecular recognition of these ligands is slow, with association rate constants orders of magnitude below the diffusional limit. Thus, we were prompted to consider strategies for increasing RNA association kinetics. Proteins can accelerate ligand association via electrostatic forces, and here, using the Tetrahymena group I ribozyme, we provide evidence that electrostatic forces can accelerate RNA/ligand association. This RNA enzyme (E) catalyzes cleavage of an oligonucleotide substrate (S) by an exogenous guanosine (G) cofactor. The G 2′- and 3′-OH groups interact with an active site metal ion, termed MC, within E·S·G, and we perturbed each of these contacts via −NH3+ substitution. New and prior data indicate that G(2′NH3+) and G(3′NH3+) bind as strongly as G, suggesting that the −NH3+ substituents of these analogues avoid repulsive interactions with MC and make alternative interactions. Unexpectedly, removal of the adjacent −OH via −H substitution to give G(2′H,3′NH3+) and G(2′NH3+,3′H) enhanced binding, in stark contrast to the deleterious effect of these substitutions on G binding. Pulse–chase experiments indicate that the −NH3+ moiety of G(2′H,3′NH3+) increases the rate of G association. These results suggest that the positively charged −NH3+ group can act as a molecular “anchor” to increase the residence time of the encounter complex and thereby enhance productive binding. Electrostatic anchors may provide a broadly applicable strategy for the development of fast binding RNA ligands and RNA-targeted therapeutics.

Electrochemical extraction of lanthanum in molten fluoride salts assisted by KF or NaF

Separation of some active metal ions such as Ce3+, Eu3+, and La3+ from molten fluoride salt using electrochemical process is difficult. The currently available electrodeposition process assisted by the solid reactive electrode or liquid metal electrode faces challenges such as the isolation of the reactive electrode due to the formation of a compound, the ability to maintain a low activity value of the active metal in liquid electrode, and a complex purification process of the target metal. In the present study, we developed a new method that successfully proved the extraction of lanthanum from molten LiF salt using an inert Mo electrode with the assistance of either NaF or KF salt. In that case, the formation of LaF63− in LiF-KF (or LiF-NaF) salt, instead of La3+ in LiF, positively shifts the electrodeposition potential of lanthanum by a value of about 1 V. The simplicity of this method compared to the conventional routes for the extraction of lanthanum from molten salt will result in a reduction in separation costs and this approach has a potential application for the separation of other active metals in molten fluorides or chlorides.

The Cardiovascular Protective Effects of Chrysin: A Narrative Review on Experimental Researches.

Chrysin is one of the flavonoids fruits, vegetables, and plant especially found in honey, it has been indicated that its cardiovascular protective effect is due to its antioxidative effects and anti-inflammatory activities. Chrysin exerts an antioxidant effect by enhancing the antioxidant system, suppressing pro-oxidant enzymes, scavenging free radicals and chelating redox active transition-metal ions. Chrysin decreases lipid synthesis and also increases its metabolism, thereby ameliorating blood lipid profile. Chrysin modulates vascular function by increasing the bioavailability of endothelial nitric oxide. Chrysin inhibits the development of atherosclerosis by decreasing vascular inflammation. The anti-inflammatory effects of chrysin may relate to its inhibitory effect on the nuclear transcriptional factor-kB signaling pathway. It also prevents vascular smooth muscle cells proliferation and thrombogenesis. Altogether, chrysin may be effective as a natural agent for the prevention and treatment of cardiovascular diseases; however, several clinical trial studies should be done to confirm its protective effects on humans.

(Invited) Gamma Irradiated WO3 Nanostructures for Electrochemical Sensing of Multiple Depression Biomarkers

Ability of smart sensors to monitor critical biomarkers even at very low concentration paves the way for further progression in precision medicine initiatives. Hence, many attempts have been made to improve sensing performances by suitably modifying the electrode materials. Surface modification by radiation (e.g. neutrons, ions, electrons and γ-rays) leads to production of lattice defects such as vacancies, defect clusters and dislocations and these induced defects act as recombination centres by trapping the generated carriers. In the present work, we report the synthesis of nanostructured WO3 and its surface modification by gamma ray and swift heavy ion irradiation with different doses and its application for electrochemical sensors applications. Identification and detection of easily obtainable biomarkers that accurately diagnoses depression are imperative for improving mental health of patients. Here, the gamma and swift heavy irradiated WO3 nanoparticles have shown very high electrocatalytic activity towards a number of neurochemicals including dopamine, serotonin, epinephrine, norepinephrine, acetylcholine, and melatonin [1-4]. For example, nicotinamide adenine dinucleotide (NAD) immobilized gamma irradiated WO3 NPs modified glassy carbon electrode has exhibited simultaneous electrochemical determination of NEP and MEL with the lowest detection limits of 1.4 nM, and 2.6 nM respectively over a wide dynamic range of 0.010 to 1000 µM in phosphate buffer solution at physiological pH of 7.0. The major improvements in the electrocatalytic activity of the fabricated electrode towards the oxidation of analytes is due to the induced high surface density defects, larger electroactive surface area, higher conductivity and fast electron kinetics. Interestingly, these electrodes exhibited excellent anti-interference 5ability against a number of active biological species and metal ions with good stability and reproducibility. Furthermore, fabricated sensors could be successfully applied for real sample analysis with human blood serum, and pharmaceutical samples and the results will be discussed in detail. References AC. Anithaa, K. Asokan, C. Sekar, Biosensors and Bioelectronics (2019)AC Anithaa, K Asokan, C Sekar, J. Taiwan Inst. Chem. Eng. 84 (2018) 11-18AC. Anithaa, K. Asokan , C. Sekar, Sens.Actuators B: Chem. B 238 (2017) 667–675AC. Anithaa K. Asokan, C. Sekar, Electrochim. Acta, 167 (2015) 294; 237 (2017) 44-53

A surface-engineered polyetheretherketone biomaterial implant with direct and immunoregulatory antibacterial activity against methicillin-resistant Staphylococcus aureus

Metal ions or nanoparticles are believed to be promising additives in developing antibacterial biomaterials, owing to possessing favorable bactericidal effects against antibiotic-resistant bacteria. However, the immunomodulatory antibacterial activity of metal ions has seldom been reported. Herein, a porous microstructure designed to trap methicillin-resistant Staphylococcus aureus (MRSA) is fabricated on polyetheretherketone biomaterial surface through sulfonation (SPEEK), following which copper (Cu) nanoparticles, which can kill the trapped MRSA, are immobilized on SPEEK surface using a customized magnetron sputtering technique. In vitro antibacterial and immunological experiments indicate that the Cu-incorporated SPEEK can exert a desirable bactericidal effect against MRSA through the combination of “trap killing” and “contact killing” actions; meanwhile, macrophages cultured on the Cu-incorporated SPEEK can be activated and polarized to a pro-inflammatory phenotype along with improved phagocytic ability on the MRSA. Further in vivo implant-associated infection models evidence the superior antibacterial activity of the Cu-incorporated SPEEK. These results demonstrate multimodal antibacterial actions of the Cu-incorporated SPEEK, which is capable of imposing direct antibacterial and indirect immunomodulatory antibacterial effects simultaneously, in order to prevent and cure MRSA infection. It is believed that this study may shed light on developing novel biomaterial implants that combine antibacterial and immunomodulatory functions.

Solid-State Electrochemical Process and Performance Optimization of Memristive Materials and Devices

As an emerging technology, memristors are nanoionic-based electrochemical systems that retains their resistance state based on the history of the applied voltage/current. They can be used for on-chip memory and storage, biologically inspired computing, and in-memory computing. However, the underlying physicochemical processes of memristors still need deeper understanding for the optimization of the device properties to meet the practical application requirements. Herein, we review recent progress in understanding the memristive mechanisms and influential factors for the optimization of memristive switching performances. We first describe the working mechanisms of memristors, including the dynamic processes of active metal ions, native oxygen ions and other active ions in ECM cells, VCM devices and ion gel-based devices, and the switching mechanisms in organic devices, along with discussions on the influential factors of the device performances. The optimization of device properties by electrode/interface engineering, types/configurations of dielectric materials and bias scheme is then illustrated. Finally, we discuss the current challenges and the future development of the memristor.

Prototype membrane electrolysis using a MFI-zeolite-coated ceramic tubular membrane provides in-line generation of two active electron mediators by eliminating active species crossover

Active ion crossover is a major obstacle in membrane electrolysis, which reduces the efficiency of the active mediator and increases operational cost. Using a prototype tubular cell divided with a MFI-zeolite-coated (shell side) ceramic tubular membrane, two active mediators, Co3+ (Co2(SO4)3) in 5 M H2SO4 at the anodic half-cell and Ni1+ ([Ni(CN)4]3-) in 9 M KOH at the cathodic half-cell, were produced. The rate of Co3+ production increased from 5.74 × 10−3 M min−1 to 7.11 × 10−3 M min−1 when the use of 9 M KOH at the cathodic half-cell instead of 5 M H2SO4 at both half-cells and controlled migration due to the pH change. The absence of a UV–visible spectral peak for cobalt or nickel ions in the other side of the electrolyzed solution supports the lack of active metal ion crossover by the MFI-zeolite-coated ceramic membrane. In high acid and base electrolyte pH, the 5.6 fold higher resistance (5.13 Ω cm−2) than in high acid electrolytes in both half-cells (0.91 Ω cm−2) prevented proton and active mediator ion crossover. SEM-EDS and XRD data profiles found no cobalt or nickel ions on the membrane, which also supports the lack of migration, whereas the Al ion concentration decreased on the lumen side (9 M KOH containing the cathodic half-cell), demonstrating the dissolution of Al2O3 in the KOH medium (uncoated MFI). The MFI-coated tubular membrane can be a good choice for the effective generation of two mediators by membrane electrolysis using high end pH electrolytes.