Cationic Peptides and Their Cu(II) and Ni(II) Complexes: Coordination and Biological Characteristics

Antimicrobial peptides are a promising group of compounds used for the treatment of infections. In some cases, metal ions are essential to activate these molecules. Examples of metalloantibiotics are, for instance, bleomycin and dermcidin. This study is focused on three new pseudopeptides with potential biological activity. The coordination behavior of all ligands with Cu(II) and Ni(II) ions has been examined. Various analytical methods such as potentiometric titration, UV-Vis and CD spectroscopies, and mass spectrometry were used. All compounds are convenient chelators for metal ion-binding. Two of the ligands tested have histidine residues. Surprisingly, imidazole nitrogen is not involved in the coordination of the metal ion. The N-terminal amino group, Dab side chains, and amide nitrogen atoms of the peptide bonds coordinated Cu(II) and Ni(II) in all the complexes formed. The cytotoxicity of three pseudopeptides and their complexes was evaluated. Moreover, their other model allowed for assessing the attenuation of LPS-induced cytotoxicity and anti-inflammatory activities were also evaluated, the results of which revealed to be very promising.     

The Causes and Potential Injurious Effects of Elevated Serum Leptin Levels in Chronic Kidney Disease Patients

Leptin is an adipokine that regulates appetite and body mass and has many other pleiotropic functions, including regulating kidney function. Increased evidence shows that chronic kidney disease (CKD) is associated with hyperleptinemia, but the reasons for this phenomenon are not fully understood. In this review, we focused on potential causes of hyperleptinemia in patients with CKD and the effects of elevated serum leptin levels on patient kidney function and cardiovascular risk. The available data indicate that the increased concentration of leptin in the blood of CKD patients may result from both decreased leptin elimination from the circulation by the kidneys (due to renal dysfunction) and increased leptin production by the adipose tissue. The overproduction of leptin by the adipose tissue could result from: (a) hyperinsulinemia; (b) chronic inflammation; and (c) significant lipid disturbances in CKD patients. Elevated leptin in CKD patients may further deteriorate kidney function and lead to increased cardiovascular risk.     

Shewanella sp. O23S as a Driving Agent of a System Utilizing Dissimilatory Arsenate-Reducing Bacteria Responsible for Self-Cleaning of Water Contaminated with Arsenic

The purpose of this study was a detailed characterization of Shewanella sp. O23S, a strain involved in arsenic transformation in ancient gold mine waters contaminated with arsenic and other heavy metals. Physiological analysis of Shewanella sp. O23S showed that it is a facultative anaerobe, capable of growth using arsenate, thiosulfate, nitrate, iron or manganite as a terminal electron acceptor, and lactate or citrate as an electron donor. The strain can grow under anaerobic conditions and utilize arsenate in the respiratory process in a broad range of temperatures (10–37 °C), pH (4–8), salinity (0%–2%), and the presence of heavy metals (Cd, Co, Cr, Cu, Mn, Mo, Se, V and Zn). Under reductive conditions this strain can simultaneously use arsenate and thiosulfate as electron acceptors and produce yellow arsenic (III) sulfide (As₂S₃) precipitate. Simulation of As-removal from water containing arsenate (2.5 mM) and thiosulfate (5 mM) showed 82.5% efficiency after 21 days of incubation at room temperature. Based on the obtained results, we have proposed a model of a microbially mediated system for self-cleaning of mine waters contaminated with arsenic, in which Shewanella sp. O23S is the main driving agent.     

The Impact of Zeta Potential and Physicochemical Properties of TiO2‐Based Nanocomposites on Their Biological Activity

The aim of this research was to observe the relationship between zeta potential, morphology, surface area, porosity, chemical composition, and ecotoxicity of nanocomposite powders such as Au/TiO₂, Ag₂O/TiO₂, PdO/TiO₂, Ag/TiO₂/SiO₂, Ag/N(C)TiO₂, and SiO₂/TiO₂ from which Ag₂O/TiO₂, Ag/N(C)/TiO_2, and Ag/TiO₂/SiO₂ were exhibiting good antimicrobial properties. It was observed, that nanomaterials characterized by similar morphology and zeta potential revealed the similar toxic behavior. The samples of higher agglomeration and higher zeta potential, especially Ag/TiO₂/SiO₂ xerogel and TiO₂/SiO₂ aerogel were generally less ecotoxic to water organisms and plants. They were also not genotoxic in concentrations up to 500 and 250 mg/L, respectively.     

Synthesis and thermal,mechanical and gas permeation properties of aromatic polyimides containing different linkage groups

Two series of aromatic polyimides containing various linkage groups based on 2,7‐bis(4‐aminophenoxy)naphthalene or 3,3′‐dimethyl‐4,4′‐diaminodiphenylmethane and different aromatic dianhydrides, namely 4,4′‐(4,4′‐isopropylidenediphenoxy)bis(phthalic anhydride), 4,4′‐(hexafluoroisopropylidene)bis(phthalic anhydride), 3,3′,4,4′ benzophenonetetracarboxylic dianhydride, 9,9‐bis[4‐(3,4‐dicarboxyphenoxy)phenyl]fluorene dianhydride and 4,4′‐(4,4′‐hexafluoroisopropylidenediphenoxy)bis(phthalic anhydride), were synthesized and compared with regard to their thermal, mechanical and gas permeation properties. All these polymers showed high thermal stability with initial decomposition temperature in the range 475–525 °C and glass transition temperature between 208 and 286 °C. Also, the polymer films presented good mechanical characteristics with tensile strength in the range 60–91 MPa and storage modulus in the range 1700–2375 MPa. The macromolecular chain packing induced by dianhydride and diamine segments was investigated by examining gas permeation through the polymer films. The relationships between chain mobility and interchain distance and the obtained values for gas permeability are discussed. © 2014 Society of Chemical Industry     

Synthesis and Interfacial Activity of Novel Heterogemini Sulfobetaines in Aqueous Solution

Three new heterogemini sulfobetaines and their chloride salts were synthesised. The interfacial activities of the obtained chlorides in aqueous solution were studied by equilibrium and dynamic surface tension measurements. The critical micelle concentration, surface excess concentration, minimum area per surfactant molecule and standard Gibbs energy of adsorption as well as micelle lifetime and diffusion coefficient were determined. The adsorption properties and micelle lifetime of these compounds significantly depend on the length of alkyl chain. The critical micelle concentration decreases with increasing chain length of the compounds considered. The values of the diffusion coefficient of N‐alkyl‐N‐methyl‐N‐(3‐sulfopropyl)‐6‐(N‐alkyl‐N‐methylamino)hexylammonium chloride tend to decrease as the concentration is increased.     

Adsorption,Electrokinetic and Stabilizing Properties of the Guar Gum/Surfactant/Alumina System

The adsorption of non‐ionic polysaccharide guar gum (GG) in the presence of surfactants (anionic SDS, non‐ionic TX‐100, cationic CTAB and their equimolar mixtures) from their NaCl solutions onto an alumina surface (Al₂O₃) was studied spectrophotometrically. This study is important in light of the many disagreements concerning the structure and behaviour of mixtures containing polymers and surfactants at the surface of an adsorbent. The presence of surfactant caused an increase in the GG adsorption in all studied systems as a consequence of the formation of complexes. Among the single surfactants the highest increase in the GG adsorption was observed in the presence of CTAB. However, the usage of mixtures of the surfactants caused a much more effective increase in the GG adsorption on the alumina surface because of the synergistic effect of the surfactants. In order to get some information on the structure of the electrical double layer (edl), the surface charge density of alumina was determined and zeta potential measurements were conducted. The obtained data showed that the adsorption of GG or GG/surfactant complexes on the metal oxide surface strongly influences a diffused part of the edl, whereas a compact part of the edl is not affected. The colloidal stability of the alumina suspensions was measured in the presence and absence of GG and surfactants. It was found that GG and the mixtures of GG and surfactants can improve the stability of the suspensions.     

Effect of the structure of polymer inclusion membranes on zn(II) transport from chloride aqueous solutions

This article presents application of polymer inclusion membranes (PIM) containing polymer matrices: cellulose triacetate (CTA) or poly(vinyl) chloride (PVC), o‐nitrophenyloctyl ether (NPOE) as a plasticizer and phosphonium ionic liquids, i.e., trihexyltetradecylphosphonium chloride (Cyphos IL 101), bis(2,4,4‐trimethylpentyl)phosphinate (Cyphos IL 104) and tributyltetradecylphosphonium chloride (Cyphos IL 167), as carriers for Zn(II) transport from chloride medium. Cyphos IL167 application as an ion carrier in PIMs is reported for the first time. The membrane composition is found to affect Zn(II) transport significantly. SEM and AFM images show the differences in the surface morphology of PVC and CTA based membranes. Better transport abilities of CTA membranes (Zn(II) recovery factors exceed 80%) compared with those of PVC, indicate that the structural differences between the two polymers play a crucial role for the membrane permeability. The best initial flux and permeability coefficient are obtained for the membranes with Cyphos IL 101 and Cyphos IL 104 as carriers. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42319.