Effect Of Common Metal Ions Research Articles

Physical and chemical properties of aluminum tailings mud modified by metal ions

Aluminum tailings mud, a type of waste generated by bauxite washing during alumina production, is harmful. Owing to the isomorphism substitution of iron-aluminum symbiotic minerals, a large number of metal ions inevitably exist in the slurry, which causes the suspension to maintain dispersion and hinders the drainage of aluminum tailings mud. This study examined the effects of the pH and commonly associated metal ions, such as K+ and Fe3+, on the sedimentation characteristics of aluminum tailings mud. Zeta potential analyzer, X-ray fluorescence spectrum analysis, and electron scanning microscopy were used to study the effects of common metal ions in the tailings slurry on the sedimentation characteristics of aluminum tailings mud. The results showed that the sedimentation effect of the tailings slurry was superior after adding Fe3+ compared with K+. The mechanism analysis shows that at a certain pH range, the addition of metal ions can compress the thickness of the electric double layer on the surface. The high-valence ions (Fe3+) will have more electric double layer compression than monovalent ions (Na+), which is more conducive to the agglomeration of aluminum tailing mud particles. This conclusion provides guidance for efficient drainage of aluminum tailings mud.

Metal-Mediated DNA Adsorption on Carboxylated, Hydroxylated, and Hydrogenated Nanodiamonds.

Nanodiamonds (NDs) have attracted considerable attention owing to their quantum properties and versatility in biological applications. In this study, we systematically investigated the adsorption of DNA oligonucleotides onto NDs with three types of surface groups: carboxylated (COOH-), hydroxylated (OH-), and hydrogenated (H-). Among them, only the H-NDs showed fluorescence quenching property that is useful for real-time DNA adsorption kinetic studies. The effect of common metal ions on DNA adsorption was studied. In the presence of Na+, the order of DNA adsorption efficiency was H- > OH- > COOH-, whereas all the NDs showed a similar DNA adsorption efficiency in the presence of divalent metal ions such as Ca2+ and Zn2+. Desorption studies revealed that hydrogen bonding and metal-mediated interactions were dominant for the adsorption of DNA, and the H-NDs exhibited extraordinarily tight DNA adsorption. Finally, a fluorescently labeled DNA was adsorbed on NDs for DNA detection, and the COOH-NDs had the highest target specificity, and a detection limit of 1.4 nM was achieved. This study indicates the feasibility of using metal ions to mediate the physical adsorption of DNA to NDs and compares various NDs with graphene oxide for fundamental understanding.

Investigation on the Binding properties of a Coumarin Derivative to Insulin by Spectroscopic and Computational Approaches

The binding properties of insulin hormone to the potential antidiabetic coumarin derivative umbelliferone (7hydroxycoumarin, 7HC) was investigated by absorption, fluorescence quenching and molecular docking methods. The negative signs of thermodynamic parameters (H and S) indicated that hydrogen bonds and van der Waals forces were dominant in the binding mode. The effect of common metal ions was investigated on binding parameters. According to the Förster’s theory; binding distance, r was obtained as 4.17 nm. The spectral data further supported by molecular docking calculations which show hydrogen bonds between 7HC and insulin.

The interaction between human serum albumin and antidiabetic agent – exenatide: determination of the mechanism binding and effect on the protein conformation by fluorescence and circular dichroism techniques - Part I

The interactions between transport proteins and drugs are very important from the pharmacological point of view. In this study, using fluorescence and circular dichroism (CD) techniques, we investigated the interaction between human serum albumin (HSA) and incretin antidiabetic drug – exenatide. Moreover, the effect of common metal ions (Ca2+, Zn2+, Cr3+) on the exenatide–HSA binding – was also described. Based on the experimental data under pseudophysiological conditions, the calculated binding constant values are on the order of 104 M−1, and the constants are lower in the presence of metal ions. We observed the increase of the hydrophobicity near the tryptophan-214 residue in subdomain IIA, but almost no change in the hydrophobicity surrounding tyrosine residues. A similar effect on the tryptophan microenvironment is influenced by metal ions. The calculated thermodynamic parameters indicated that the characteristic electrostatic and hydrophobic interactions play an important role in the albumin–exenatide complexes. The CD studies showed that exenatide does not change the secondary structure of the protein but used metal ions have some impact on albumin α-helical content.Communicated by Ramaswamy H. Sarma

Synthesis, photophysical studies, and application of novel 2,7-bis((1-butyl-1H-1,2,3-triazol-4-yl)methoxy)naphthalene as a highly selective, reversible fluorescence chemosensor for detection Fe3+ ions

The new reversible turn-off fluorescence chemosensor 2,7-bis((1-butyl-1H-1,2,3-triazol-4-yl)methoxy)naphthalene for selective detection of Fe3+ ions has been designed and synthesized using a multicomponent approach. The absorption and emission characteristics of this new chemosensor were studied in different solvents of varying polarities. The ground and excited state dipole moments were determined experimentally by solvatochromic methods and theoretically using DFT/TD-DFT calculations. The effect of common metal ions on emission spectra was investigated. The results showed that it can be used as reversible turn-off fluorescence chemosensor to determine Fe3+ ions with high selectivity among a series of other common cations. The binding stoichiometry of chemosensor with Fe3+ ions and association constant was investigated using global fit analyses as proposed by Thordarson. The mechanism of fluorescence quenching was studied by using a Stern-Volmer plot. The linear range of the chemosensor for detection of Fe3+ ions was found to be 8.0×10−7M to 1.0×10−5M with limit of detection (LOD) of 8.7×10−7M and limit of quantification (LOQ) of 2.6×10−6M. The Frontier molecular orbitals (FMO) analysis and chemical reactivity indices of this new chemosensor were also studied using DFT/TD-DFT calculations. The non-linear optical properties were also investigated. The values of total polarizability and first-order hyperpolarizability for the chemosensor were found to be higher than the standard urea molecule. Thus it can also be used as a potential NLO material. The thermodynamic parameters were also investigated.

Effect of Common Metal Ions and Anions on Laccase Catalysis of Guaiacol and Lignocellulosic Fiber

The effects of 12 common metal ionic compounds on the laccase catalytic activity in reactions using guaiacol as the substrate was determined using spectrophotometry. Furthermore, the influence of several metal ionic compounds on the generation of reactive oxygen species (ROS) by oxidation of lignin in jute fiber under laccase catalysis was studied by electron paramagnetic resonance (EPR) spectroscopy using N-tert-butyl-alpha-phenylnitrone (PBN) as the spin-trapping agent. Common metal cations, such as K+, Na+, Mg2+, Ca2+, and Cu2+ and the anion SO42- had almost no effect on laccase activity during the initial stage of the catalytic reactions. High concentrations of the Mn2+ ion exhibited weak inhibition of laccase; Ag+ and NO3- showed a moderate inhibitory effect on laccase activity during the initial stage of the catalytic reactions. Fe2+ had no direct effect on the binding of laccase to its substrate, but strongly retarded the progress of the catalytic reaction by reducing the intermediate free radicals. The ions Cl-, Fe3+, and Ag+ exhibited either strong inhibitory effects on the catalysis of the substrate or a destructive effect on the structure of laccase itself. Furthermore, the results showed that an appropriate concentration of Cu2+ helped to promote the thermal stability of laccase during the enzymatic reaction. This study could help researchers to avoid the use of inhibitory exogenous metal ions and anions in the application of laccase and to maximize the value of laccase.

Synthesis and application of thiol-functionalized magnetic nanoparticles for studying interactions of epirubicin hydrochloride with bovine serum albumin by fluorescence spectrometry.

A novel method was developed for studying the interaction between epirubicin hydrochloride (EPI) and bovine serum albumin (BSA) by fluorescence spectrometry. Fe3 O4 magnetic nanoparticles (MNPs) synthesized and functionalized with thiol group were employed for the immobilization and separation of target BSA in reaction solutions. The concentrations of the non-immobilized BSA and unbound EPI were obtained separately by fluorescence spectrometry. The binding constants (Ka ) and number of binding sites (n) of EPI with BSA were calculated. In this study, the Ka value was 5.05×105 L mol-1 , suggesting a strong binding of EPI to BSA, and the n value was 1.15. The effects of common metal ions on Ka of EPI with BSA were also investigated, and the results showed there was clearly bindings between the metal ions and BSA. The precise binding sites of EPI on BSA were determined as being in site I from the competitive displacement experiments. Copyright © 2016 John Wiley & Sons, Ltd.

Study of Binding Properties Between Two New Ibuprofen and Naproxen Based Acyl Hydrazone Derivatives and Trypsin.

Two acyl hydrazone derivatives, AHI and AHN,made from ibuprofen and naproxen-derived hydrazides, were prepared and studied of binding properties with serine protease trypsin by UV-vis absorption and fluorescence quenching at pH 7.4. The results suggest that both hydrazones can interact strongly with trypsin and there are the formation of trypsin-hydrazone complexes. The Stern-Volmer constants, binding constants,binding sites and the corresponding thermodynamic parameters ΔH°, ΔS° and ΔG° were calculated at different temperatures.The effect of common metal ions on the constants was also discussed. The binding modes can be explained on the basis of hydrogen bonds and van der Waals forces. The binding distance(r) ~3 nm between the donor (trypsin) and acceptors (AHI and AHN) was obtained according to Förster's non-radiative energy transfer theory. Moreover, LOD and LOQ of hydrazones were calculated in the presence of trypsin.

Synthesis of novel fluorescence xanthene–aminoquinoline conjugates, determination of dipole moment and selective fluorescence chemosensor for Th4+ ions

A series of xanthene–aminoquinoline conjugates were synthesized by following a two step procedure. All new compounds were characterized by spectral data and single crystal X-ray crystallography. Xanthene–aminoquinoline conjugates showed strong fluorescence in solution. The effect of solvent polarity, ground and excited state dipole moments of compound 2a were investigated. The ground state dipole moment was estimated to be 0.262D, while excited state dipole moment was found in the range of 9.882–1.996D. The effect of common metal ions on fluorescence spectra of compound 2a was also investigated. Compound 2a acts as a fluorescence chemosensor for selective detection of Th4+ ions in solution with linear range of 1×10−7M to 1×10−5M and detection limit of 87μM.

Interaction of norfloxacin with bovine serum albumin studied by different spectrometric methods; displacement studies, molecular modeling and chemometrics approaches

Serum albumins as major target proteins can bind to other ligands leading to alteration of their pharmacological properties. The mechanism of interaction between norfloxacin (NFLX) with bovine serum albumin (BSA) was investigated. Fuorescence quenching of serum albumin by this drug was found to be a static quenching process. The binding sites number, n, apparent binding constant, K, and thermodynamic parameters were calculated at different temperatures. The distance, r, between donor, BSA, and acceptor, NFLX, was calculated according to the Forster theory of non-radiation energy transfer. Also binding characteristics of NFLX with BSA together with its displacement from its binding site by kanamycin and effect of common metal ions on binding constant were investigated by the spectroscopic methods. The conformational change in the secondary structure of BSA upon interaction with NFLX was investigated qualitatively from synchronous fluorescence spectra, Fourier Transform Infrared (FTIR) and circular dichroism (CD) spectrometric methods. Molecular docking studies were performed to obtain information on the possible residues involved in the interaction process and changes in accessible surface area of the interacting residues. The results showed that the conformation of BSA changed in the presence of NFLX. For the first time, displacement studies were used for this interaction; displacement studies showed that NFLX was displaced by phenylbutazon and ketoprofen but was not displaced by ibuprofen indicating that the binding site of NFLX on albumin was site I. In addition a powerful chemometrics method, multivariate curve resolution-alternating least square, was used for resolution of spectroscopic augmented data obtained in two different titration modes in order to extract spectral information regardless of spectral overlapping of components.

Fluorescence interaction and determination of sulfathiazole with trypsin.

The mechanism of interaction of trypsin with the sulfathiazole was studied through using fluorescence quenching and UV-visible absorption spectra at pH 7.4. The Stern-Volmer quenching constants, binding constants, number of binding sites and the corresponding thermodynamic parameters ΔH(o), ΔS(o) and ΔG(o) were calculated at different temperatures. The effect of common metal ions on the constants was also discussed. The results suggest that sulfathiazole can interact strongly trypsin and that there is the formation of trypsin-sulfathiazole complex and the interaction can be explained on the basis of hydrogen bonds and van der Waals forces. The binding distance (r) between the donor (trypsin) and acceptor (sulfathiazole) was 3.52 nm based on the Förster's non-radiative energy transfer theory. The detection and quantification limits of sulfathiazole were calculated as 2.52 and 8.40 μM in the presence of trypsin, respectively. The relative standard deviation (RSD) was 4.086% for determinations (n = 7) of a sulfathiazole solution with the concentration of 7.54 μM.

Studies on the interaction of palmatine hydrochloride with bovine hemoglobin

The interaction between bovine hemoglobin (BHb) and palmatine hydrochloride (PMT) was investigated at different temperatures using multispectroscopy, as well as the effect of common metal ions (Ca(2+) , Mg(2+) , Zn(2+) , Cu(2+) , Fe(2+) , Fe(3+) , Co(2+) , Ni(2+) ) on the BHb-PMT system. Results showed that the quenching mechanism of PMT on BHb was a static process. The electrostatic force played an important role in the conjugation reaction between BHb and PMT. The order of magnitude of the binding constants (Ka ) was 10(4) , and the number of binding sites (n) in the binary system was ~ 1. The binding distance (r) was ~ 2.44 nm and the primary binding for PMT was located at β-37 tryptophan in the hydrophobic cavity of BHb. In addition, the Hill's coefficients were ~ 1. Synchronous and circular dichroism spectra revealed that the microenvironment and the conformation of BHb were changed during the binding reaction.

Interaction of Cefpiramide sodium with bovine hemoglobin and effect of the coexistent metal ion on the protein-drug association

The interaction between bovine hemoglobin (BHb) and cefpiramide sodium (CPMS) was investigated at different temperatures by fluorescence, UV absorption, and CD spectroscopy, as well as the effect of common metal ions (Mg2+, Zn2+, Cu2+, Co2+, Fe3+, Ni2+) on the BHb–CPMS system. Results showed that CPMS could quench the intrinsic fluorescence of BHb strongly, and the quenching mechanism was a static quenching process. The electrostatic force played an important role on the conjugation reaction between BHb and CPMS. The order of magnitude of binding constants (Ka) was 104, the number of binding site (n) in the binary system was approximately equal to 1 and the binding distance (r) was about 3.08nm. Besides, the values of Hill's coefficients were approximately equal to 1, which indicated there was almost no cooperativity in CPMS's binding with BHb. Synchronous spectra and CD spectra revealed that the microenvironment and the conformation of BHb were changed during the binding reaction. Studies on the interaction between BHb and drug will facilitate interpretation of the drug's metabolism and transporting process in the blood, and will help to explain the relationship between structures and functions of BHb.

Interaction of Salicylic Acid with Bovine Hemoglobin and Effect of the Coexistent Metal Ion on the Reaction

ABSTRACT The interaction between bovine hemoglobin (BHb) and salicylic acid (SA) was investigated at different temperatures by fluorescence spectroscopy, as was the effect of common metal ions (Mg2+, Zn2+, Cu2+, Co2+, Fe3+, Ni2+) on the BHb–SA system. Results showed that the quenching mechanism of SA on BHb was a static quenching process. The electrostatic force played an important role in the conjugation reaction between BHb and SA. Besides, the values of Hill's coefficients were approximately equal to 1. Synchronous and CD spectra revealed that the microenvironment and the conformation of BHb were changed during the binding reaction.

Effect of common metal ions on the rate of degradation of 4-nitrophenol by a laccase-Cu2+ synergistic system

Various metal ions are present in industrial wastewater. In this study, the role of Cu2+ in pollutant degradation by laccase and the effect of common metal ions such as Na+, K+, Ca2+, Mg2+, Zn2+, Hg2+, Mn2+, Fe2+, Co2+, Ni2+, Fe3+, and Al3+ on the degradation velocity of the laccase-Cu2+ synergistic system using 4-nitrophenol as the target pollutant were investigated. The results show that the laccase-Cu2+ system achieved a higher degradation velocity than the system without Cu2+. The activity of the laccase-Cu2+ synergistic system was inhibited when a monovalent metal ion (Na+ or K+) was added into the system regardless of the concentration. The addition of relatively low concentrations of any divalent metal ions also resulted in inhibition of the activity. However, increasing concentrations of Ca2+ or Fe2+ increased the rate of degradation of 4-nitrophenol by the laccase-Cu2+ system, whereas increasing concentrations of other divalent metal ions suppressed the system. The inhibition effect of the added trivalent metal ions (Al3+ or Fe3+) was significant during the entire process, indicating that these trivalent metal ions can be a serious obstacle to the activity of the laccase-Cu2+ synergistic system.

Study on the conjugation mechanism of colistin sulfate with bovine serum albumin and effect of the metal ions on the reaction

Colistin sulfate (CS) can quench the fluorescence of bovine serum albumin (BSA) in an aqueous solution at pH 7.40. The static fluorescence-quenching process between BSA and CS was confirmed and the binding constant, the number of binding sites and thermodynamic data for the interaction between BSA and CS were also obtained. Results showed that the order of magnitude of binding constant (Ka) was 104, and the number of binding site (n) in the binary system was approximately equal to 1; electrostatic force played an important role on the conjugation reaction between BSA and CS. On the basis of the Förster theory of the resonance energy transfer, the binding distance (r) between CS and BSA was less than 7nm. Comparing the quenching of protein fluorescence excited at 280nm and 295nm and from the site marker replacement experiments, it was shown that the primary CS binding site was located in the sub-domain IIA (site I) of BSA. Synchronous fluorescence spectra clearly revealed that the binding of CS with BSA can induce conformation changes in BSA. In addition, the effects of common metal ions on the binding constants of CS–BSA complex were also discussed. It was shown that, except Cu2+, the high metal ion concentrations improved the CS efficacy.

头孢匹胺钠与牛血清白蛋白的相互作用机理及共存金属离子的影响

The interaction between bovine serum albumin(BSA) and cefpiramide sodium(CPMS) was investigated at different temperatures.The effect of common metal ions(Mg2+,Zn2+,Cu2+,Co2+,Fe3+,Ni2+) on the BSA-CPMS system was also researched.The results show that CPMS can quench the intrinsic fluorescence of BSA significantly,and the quenching mechanism is a static quenching process which follows the Frester spectroscopy energy transfer.The electrostatic force played an important role on the conjugation reaction between BSA and CPMS.The binding constants(Ka) was in the order of 104,and the number of binding site(n) in the binary system was approximately equal to 1.The binding distance(r) was about 2.60 nm and the primary binding for CPMS was located at sub-domainⅡA of BSA.Synchronous spectra and Circular dichroism(CD) spectra revealed that the microenvironment and the conformation of BSA were changed during the conjugation reaction.

Study on the Interaction Mechanism of Lysozyme and Bromophenol Blue by Fluorescence Spectroscopy

The interaction of lysozyme with bromophenol blue (BPB) in acetate buffer (pH 6.0) was studied by fluorescence quenching method for the first time. It was found that BPB could conspicuously quench the fluorescence of lysozyme by the static quenching process, possibly due to the binding on the active site near Trp62. The binding parameters including the binding constant and the number of binding site were calculated. The thermodynamic parameters DeltaH degrees, DeltaS degrees and DeltaG degrees at different temperatures were obtained. The formation of lysozyme-BPB complex depended on the cooperation of the hydrophobic and electrostatic forces. And the binding average distance between lysozyme and BPB was determined. The effect of common metal ions on the binding constant of lysozyme-BPB was also examined.

Effects of common metal ions on the determination of anions by suppressed ion chromatography

The effects of common metal ions (Na +, K +, Ca 2+, Mg 2+, Al 3+ and Fe 3+) on the determination of nitrate, phosphate and sulfate by suppressed ion chromatography were investigated. The responses of nitrate within 1–10 mg/l were not affected in the presence of six metal ions at 10 mg/l. The peak areas of 1.0 mg/l sulfate increased significantly at 10 mg/l Fe 3+ or Al 3+ up to 51.34 and 48.37%, respectively. In the presence of 10 mg/l Fe 3+, the peak area of 1 mg/l and 10 mg/l phosphates decreased by 91.44 and 33.71%, respectively. At 10 mg/l Al 3+ the peak areas of phosphate also increased slightly. The adverse effect of Fe 3+ on the determination of phosphate could be overcome effectively by reducing the pH of the samples. The method to overcome the adverse effect was studied.