Concomitant degradation of bisphenol A during ultrasonication and Fenton oxidation and production of biofertilizer from wastewater sludge

Degradation of bisphenol A (BPA), an endocrine disruptor, from wastewater sludge (WWS) has attracted great interest recently. In the present study, the effects of different pre-treatment methods, including ultrasonication (US), Fenton's oxidation (FO) and ferro-sonication (FS) was assessed in terms of increase in solubilization of WWS and simultaneous degradation of BPA. Among US, FO and FS pre-treatment, higher suspended solids (SS), volatile suspended solids (VSS), chemical oxygen demand (COD) and soluble organic carbon (SOC) solubilization (39.7%, 51.2%, 64.5% and 17.6%, respectively) was observed during a ferro-sonication pre-treatment process carried out for 180 min, resulting in higher degradation of BPA (82.7%). In addition, the effect of rheological parameters (viscosity and particle size) and zeta potential on the degradation of BPA in raw and different pre-treated sludges were also investigated. The results showed that a decrease in viscosity and particle size and an increase in zeta potential resulted in higher degradation of BPA. BPA degradation by laccases produced by Sinorhizobium meliloti in raw and pre-treated sludge was also determined. Higher activity of laccases (207.9 U L(-1)) was observed in ferro-sonicated pre-treated sludge (180 min ultrasonic time), resulting in higher removal of BPA (0.083 μg g(-1)), suggesting concomitant biological degradation of BPA.     

Orientation selective ESEEM studies on the blue oxidases laccase and ascorbate oxidase

The blue oxidases, laccase and ascorbate oxidase, contain three spectroscopically distinct copper binding sites, two of which are EPR detectable in the oxidized Cu(II) state, called type 1 (T1) and type 2 (T2). The three dimensional structure of ascorbate oxidase has recently been determined (Messerschmidt A.et al.: J. Mol. Biol.206, 513 (1989)) while that of laccase has not. We have therefore carried out comparative electron spin echo envelope modulation (ESEEM) measurements on ascorbate oxidase, laccase and laccase in which T1 Cu(II) was substituted with Hg(II) in order to obtain structural information about the copper sites in laccase. The ESEEM results clearly show that there are as many histidines in laccase as in ascorbate oxidase, i.e., at least two at each site. Orientation selective ESEEM experiments showed that in the T1 site in both enzymes the two remote (uncoordinated) nitrogens are magnetically inequivalent and have different hyperfine interactions. Furthermore, the isotropic hyperfine constants of both remote nitrogens in laccase T1 are larger than those in ascorbate oxidase T1. In laccase T2 two remote nitrogens show similar hyperfine couplings and the modulation depth is significantly deeper than in ascorbate oxidase. Finally, it is suggested that the difference between the NQR frequencies of the remote nitrogens in T1 and T2 in both oxidases can be attributed to the alkyl group of the side chain being adjacent to the bound imidazole in T1 and to the remote nitrogen in T2. This is in accordance with the known X-ray structure of ascorbate oxidase.     

金属离子辅助高静压钝化树莓多酚氧化酶研究

 树莓多酚氧化酶具有较强的耐压性,在600 MPa压力下处理45 min,其残余酶活仍高达40%以上。为了进一步钝化树莓内源多酚氧化酶的活性,研究了金属离子辅助高静压对树莓多酚氧化酶钝化的影响。在树莓多酚氧化酶粗酶液中添加对酶活性有抑制、激活、无改变的金属离子,研究其辅助400、600 MPa压力处理钝化树莓多酚氧化酶的效果。发现添加金属离子后,多酚氧化酶的活性随压力增大、时间延长而降低;Fe²⁺、Mn²⁺以及Cu²⁺均有不同程度的协同高静压钝化作用,而Ca²⁺在钝化树莓多酚氧化酶时与高静压出现拮抗现象,对树莓多酚氧化酶活性无影响的Zn²⁺未出现协同/拮抗作用。     

Creating planar electrode systems for biosensors

A planar topology for a nanoelectronic transducer based on glucose oxidase is designed for use in an enzymatic biosensor. Electromigration is used to create 5-nm gaps in Au nanowires. A method for the chemical modification of a silica surface with epoxysilane is developed and glucose oxidase is immobilized on the surface of a support by means of linking molecules. A technique for biochemical signal registration is developed. The eelectric response of the biosensor with glucose in a test solution and the dependence of this response on the glucose concentration are investigated.     

Polyaniline biosensor for choline determination

Choline oxidase has been immobilized inside nanostructured polyaniline layers of a controlled porosity and a micrometer or nanometer thickness to form a choline sensor: polyaniline-choline oxidase (PChO) biosensor. Electrochemical techniques were used either, to prepare polyaniline films of a controlled thickness and to immobilize the enzyme molecules. The electrical response of a PChO sensor depends on choline concentration and its sensitivity reaches a value of 5 μA/mM in the amperometric mode and of 10 mV/mM in the potentiometric mode of measurements. The current response measured at a constant potential of +0.4 V is linear vs. choline concentration. No interference with ascorbic acid has been found. The storage stability is very satisfied: the sensors examined did not change essentially their electrical response even after a month of storage.     

Protein-Based Biosensors for Diabetic Patients

In this article we show the recent progress in the field of glucose sensing based on the utilization of enzymes and proteins as probes for stable and non-consuming fluorescence biosensors. We developed a new methodology for glucose sensing using inactive forms of enzymes such as the glucose oxidase from Aspergillus niger, the glucose dehydrogenase from the thermophilic microorganism Thermoplasma acidophilum, and the glucokinase from the thermophilic eubacterium Bacillus stearothermophilus. Glucose oxidase was rendered inactive by removal of the FAD cofactor. The resulting apo-glucose oxidase still binds glucose as observed from a decrease in its intrinsic tryptophan fluorescence. 8-Anilino-1-naphthalene sulfonic acid was found to bind spontaneously to apo-glucose oxidase as seen from an enhancement of the ANS fluorescence. The steady state intensity of the bound ANS decreased 25% upon binding of glucose, and the mean lifetime of the bound ANS decreased about 40%. These spectral changes occurred with a midpoint from 10 to 20 mM glucose, which is comparable to the KD of holo-glucose oxidase. The ANS-labeled apo-glucose dehydrogenase from Thermoplasma acidophilum also displayed an approximate 25% decrease in emission intensity upon binding glucose. This decrease can be also used to measure the glucose concentration. The thermophilic apo-glucose dehydrogenase was also stable in the presence of organic solvents, allowing determination of glucose in the presence of acetone. The third enzyme used for glucose sensing was the glucokinase from Bacillus stearothermophilus. A fluorescence competitive assay for the determination of glucose was developed based on the utilization of this thermostable enzyme. Taken together, our results show that enzymes which use glucose as their substrate can be used as reversible and non-consuming glucose biosensors in the absence of required co-factors. Moreover, the possibility of using inactive apo-enzymes for a reversible sensor greatly expands the range of proteins which can be used as sensors, not only for glucose, but for a wide variety of biochemically relevant analytes.     

Immobilization of cholesterol oxidase to finely dispersed silica-coated maghemite nanoparticles based magnetic fluid

In the recent years, the potential applicability of magnetic nanoparticles (MNPs) has witnessed a significant increase in interest towards the medical field, in particular, towards the usage of novel nanoparticles in diagnostics and disease treatment, respectively. In a present study, cholesterol oxidase (ChOx) was covalently immobilized to magnetic nanoparticles of maghemite (γ-Fe₂O₃) and further functionalized by silica (SiO₂) and amino-silane molecules. The activity of the bound enzyme was retained up to 60%, respectively. The binding of cholesterol oxidase was confirmed using FT-IR spectrophotometer. SEM analysis showed uniformly dispersed functional magnetic nanoparticles, which ranged in size from 22.5 to 50.8 nm, surrounded by amorphous silica. In this paper, the potential applications of chemically modified magnetic nanoparticles as carriers for cholesterol oxidase and other enzymes are discussed.     

Immobilization of galactose oxidase on self‐assembled monolayers of thiols on Au and Ag surfaces

Galactose oxidase (GalOD) was immobilized on self‐assembled monolayers of thiols on silver and gold surfaces using trans‐stilbene (4,4′‐diisothiocyanate)‐2,2′disulphonic acid (DIDS) as the bridging compound. DIDS is the symmetrical bifunctional reagent that reacted with the amine moiety of the thiol and with primary amino groups of enzyme. The Raman measurement revealed that onto cysteamine‐modified silver and gold electrodes, bands corresponding to the galactose oxidase (about 694, 1076, 1274 cm^—1 on Au and 762, 1058, 1274 cm^–1 on Ag ) appeared and clearly demonstrated its immobilization onto Au and Ag surfaces. Simultaneously, we have also observed changes in the ratio of trans–gauche conformers of adsorbed cysteamine molecules. Layers revealing high content of trans conformer are transformed into layers composed mainly of cysteamine molecule in gauche conformation after galactose oxidase adsorption. These observations deliver a strong support for enzyme immobilization on cysteamine‐modified gold and silver surfaces. The surface plasmon resonance experiment gave a surface coverage of ~8.4 × 10⁷ g/cm² for gold electrode modified cysteamine using DIDS chemistry and 1.1 × 10⁷ g/cm² for the cysteamine only modified gold substrate and demonstrated that galactose oxidase layers immobilized with DIDS coupling reagent are quite stable and cannot be easily removed from the surface by treatment with a buffer solution. The surface plasmon resonance results indicated that in this method, a multilayer of galactose oxidase have been immobilized. Our new method of covalent attachment of enzymes seems to be quite promising as a new way of manufacturing biosensors. Copyright © 2012 John Wiley & Sons, Ltd.     

The Mo−OH proton of the low-pH form of sulfite oxidase: Comparison of the hyperfine interactions obtained from pulsed ENDOR, CW-EPR and ESEEM measurements

Pulsed electron nuclear double resonance (ENDOR) spectra have been obtained for the exchangeable Mo-OH proton of the low-pH form of native chicken liver sulfite oxidase (SO) and recombinant human SO for the first time. The spectra of the two enzymes are very similar, indicating a similar binding geometry of the hydroxyl ligand to the Mo center. The isotropic hyperfine interaction (hfi) constant for the proton of the OH ligand in both enzymes is about 26 MHz. The anisotropic components of the hfi obtained from the pulsed ENDOR spectra are about 1.6–1.8 times larger than those obtained by continuous-wave electron paramagnetic resonance and electron spin echo envelope modulation. These hfi differences are explained by a rotational disorder of the Mo-OH group. A similar rotational disorder of the coordinated exchangeable ligand has been found previously for the high-pH and phosphate-inhibited forms of SO.     

The evaluation of 1-tetralone and 4-chromanone derivatives as inhibitors of monoamine oxidase

Molecular Diversity - Monoamine oxidase (MAO) is of much clinical relevance, and inhibitors of this enzyme are used in the treatment for neuropsychiatric and neurodegenerative disorders such as...     

Template-assisted fabrication of protein nanocapsules

Bionanomaterials have recently begun to spark a great amount of interest and could potentially revolutionize biomedical research. Nanoparticles, nanocapsules, and nanotubular structures are becoming attractive options in drug and gene delivery. The size of the delivery vehicles greatly impacts cellular uptake and makes it highly desirable to precisely control the diameter and length of nanocarriers to make uniform nanoparticles at low cost. Carbon nanotubes have shown great potential within the field of drug and gene delivery. However, their insolubility and cytotoxicity could severely delay FDA approval. A desirable alternative would be to fabricate nanostructures from biomaterials such as proteins, peptides, or liposomes, which are already FDA approved. In this article we demonstrate the preparation of protein nanocapsules with both ends sealed using a template-assisted alternate immersion method combined with controlled cleaving. Glucose oxidase nanocapsules with controllable diameter, wall thickness, and length were fabricated and characterized with SEM and TEM. The biochemical activity of glucose oxidase in the form of nanocapsules after processing was confirmed using UV spectrometry. Our future work will explore proteins suitable for drug encapsulation and cellular uptake and will focus on optimizing the cleaving process to gain precise control over the length of the nanocapsules.     

Application of polyaniline as enzyme based biosensor

The PANI films have been synthesized electrochemically and are used as matrix for immobilization of glucose oxidase (GOD) and lactate dehydrogenase (LDH) enzymes. The temporal aspects of anion self-exchange in PANI films have been investigated. The exchange of bulkier tosylate–ferricyanide ion with Cl⁻ ion has been monitored by photometry and electrochemical techniques. The relative changes in porosity brought about by self-exchange have been experimentally determined to be 323 and 2125/k in tosylate-exchanged and ferricyanide-exchanged polyaniline films, respectively. It is seen that the polyaniline films exhibit enhanced loading of glucose oxidase after a self-ion exchange, and, hence they can be used for the fabrication of a third generation glucose biosensor.Lactate is determined by the photometric detection of NADH formed in the reaction catalysed by LDH. Studies have been carried out with PANI as a matrix for the immobilization of LDH and its feasibility as a biosensor. The results of the photometric and amperometric measurements conducted on such LDH/PANI electrodes show a response to pyruvate concentration upto 0.45 mM, a response time of 90 s and a shelf life of about two weeks.     

Alteration in the plasma concentration of a DAAO inhibitor, 3-methylpyrazole-5-carboxylic acid, in the ketamine-treated rats and the influence on the pharmacokinetics of plasma D-tryptophan

A determination method for 3-methylpyrazole-5-carboxylic acid (MPC), an inhibitor of D-amino acid oxidase (DAAO), in rat plasma was developed by using high-performance liquid chromatography-mass spectrometry (LC-MS). The structural isomer of MPC, 3-methylpyrazole-4-carboxylic acid, was used as an internal standard, and the intra- and inter-day accuracies and precisions were satisfactory for the determination of plasma MPC.Next, the LC-MS method was applied to determine the plasma MPC concentration in ketamine (Ket)-treated rats after intraperitoneal administration of MPC (5.0 or 50 mg·kg(-1)). The C(max) value of plasma MPC concentration in the Ket-treated rats was significantly higher than that in the control group when a high dose of MPC (50 mg·kg(-1)) was administered. In addition, it was found that plasma D-tryptophan (D-Trp) concentration in Ket-treated rats administered D-Trp was not significantly increased by MPC, suggesting that the DAAO-inhibitory effect of MPC is attenuated in Ket-treated rats.     

Fundamentals of synchronization in chaotic systems,concepts, and applications

The field of chaotic synchronization has grown considerably since its advent in 1990. Several subdisciplines and "cottage industries" have emerged that have taken on bona fide lives of their own. Our purpose in this paper is to collect results from these various areas in a review article format with a tutorial emphasis. Fundamentals of chaotic synchronization are reviewed first with emphases on the geometry of synchronization and stability criteria. Several widely used coupling configurations are examined and, when available, experimental demonstrations of their success (generally with chaotic circuit systems) are described. Particular focus is given to the recent notion of synchronous substitution-a method to synchronize chaotic systems using a larger class of scalar chaotic coupling signals than previously thought possible. Connections between this technique and well-known control theory results are also outlined. Extensions of the technique are presented that allow so-called hyperchaotic systems (systems with more than one positive Lyapunov exponent) to be synchronized. Several proposals for "secure" communication schemes have been advanced; major ones are reviewed and their strengths and weaknesses are touched upon. Arrays of coupled chaotic systems have received a great deal of attention lately and have spawned a host of interesting and, in some cases, counterintuitive phenomena including bursting above synchronization thresholds, destabilizing transitions as coupling increases (short-wavelength bifurcations), and riddled basins. In addition, a general mathematical framework for analyzing the stability of arrays with arbitrary coupling configurations is outlined. Finally, the topic of generalized synchronization is discussed, along with data analysis techniques that can be used to decide whether two systems satisfy the mathematical requirements of generalized synchronization. (c) 1997 American Institute of Physics.     

Covalent immobilization of glucose oxidase onto Poly(St-GMA-NaSS) monodisperse microspheres via BSA as spacer arm

In this study, the immobilization of glucose oxidase (GOD) onto micron-size monodisperse Poly(Styrene-Glycidyl Methacrylate-Sodium Sulfonate Styrene) microspheres was investigated. In order to improve their surface biocompatibility, bovine serum albumin (BSA) was introduced onto the microspheres’ surface as a new type of spacer arm. Both the immobilization amount and enzymatic activity were determined in different experimental conditions (enzyme concentration, pH, temperature, etc.). It was found that BSA could serve as a good spacer because it increases both the immobilization amount and enzymatic activity of GOD. The tolerance of immobilized GOD against pH, temperatures was examined. Moreover, the kinetic parameters for native and immobilized GOD were obtained and compared.     

A short review on stable metal nanoparticles using ionic liquids,supported ionic liquids,and poly(ionic liquids)

Metal nanoparticles (NPs) are a subject of global interest in research community due to their diverse applications in various fields of science. The stabilization of these metal NPs is of great concern in order to avoid their agglomerization during their applications. There is a huge pool of cations and anions available for the selection of ionic liquids (ILs) as stabilizers for the synthesis of metal NPs. ILs are known for their tunable nature allowing the fine tuning of NPs size and solubility by varying the substitutions on the heteroatom as well as the counter anions. However, there has been a debate over the stability of metal NPs stabilized by ILs over a long period of time and also upon their recycling and reuse in organocatalytic reactions. ILs covalently attached to solid supports (SILLPs) have given a new dimension for the stabilization of metal NPs as well as their separation, recovery, and reuse in organocatalytic reactions. Poly(ILs) (PILs) or polyelectrolytes have created a significant revolution in the polymer science owing to their characteristic properties of polymers as well as ILs. This dual behavior of PILs has facilitated the stabilization of PIL-stabilized metal NPs over a long period of time with negligible or no change in particle size, stability, and size distribution upon recycling in catalysis. This review provides an insight into the different types of imidazolium-based ILs, supported ILs, and PILs used so far for the stabilization of metal NPs and their applications as a function of their cations and counter anions.     

Simultaneous measurement of particle size, velocity, andtemperature in thermal plasmas

The in-flight measurement of particle parameters (size, velocity, temperature, and local number density) can prove insight into the plasma processing of solid materials. A measurement technique for simultaneously obtaining the size, velocity, and temperature of particles entrained in high-temperature flow fields is described. Particle size and velocity are obtained from a combination laser-particle-sizing system and laser Doppler velocimeter. The particle temperature is determined by a two-color pyrometry technique and the data rate is a measure of relative particle number density. Typical measured temperatures and velocities for the 5-100 μm particles used in plasma spraying are 1600-3500 K and 100-300 m/s, respectively. Since particle size, velocity, and temperature are measured simultaneously, cold particles (<1600 K) are identified and their relative number density can be quantified. Data from two plasma spray systems, a metal one (Ni-Al) and a metal oxide one (Al₂O₃), are presented and their application to understanding the plasma spray-coating process is illustrated     

Co-immobilization of cholesterol esterase,cholesterol oxidase and peroxidase onto alkylamine glass beads for measurement of total cholesterol in serum

Commercially available cholesterol esterase, cholesterol oxidase and peroxidase have been co-immobilized onto alkylamine glass beads (pore diameter 55 nm) through glutaraldehyde coupling with a conjugation yield of 2.3 mg/g of support and 76% retention of initial activity. The co-immobilized enzyme system showed maximum activity at pH 7.0, when incubated at 37 °C for 12 min. A method was developed for total serum cholesterol determination employing co-immobilized enzymes. There was a linear relationship between A₅₂₀ and cholesteryl acetate concentration ranging from 5 mg to 50 mg/dl reaction mixture. The minimum detection limit of the method is 50 mg/dl. Within day and between day coefficient of variation were <1.0% and <6%, respectively. A good correlation (r=0.83) was found between the total serum cholesterol obtained by the present method and commercial Enzo-kit method employing free enzymes. Among the various serum substances tested at their physiological concentrations; Testosterone, vit D and progesterone caused 59%, 41% and 39% inhibition, while NaCl, KCl, CuSO₄, creatinine, NaHCO₃, albumin and estrogen had practically no effect.     

Investigation of Bioimpacts of Metallic and Metallic Oxide Nanostructured Materials: Size,Shape, Chemical Composition,and Surface Functionality: A Review

Nanotechnology is set to impact a wide range of various fields, including medicine, materials technology, environmental sciences, and engineering/manufacturing. Nanoparticles are categorized depending on their size, composition, shape, and surface functionality. Due to the excessive growth of nanostructured materials (NSMs) in production and industrial applications, human and environmental exposure to them and their possible toxicity issues are inevitable. The main objective of this review is to study NSMs, in particular metallic and metallic oxide nanoparticles, and properties that have a determinative role in their bioimpacts. Nevertheless, the main focus is to provide an overview of NSMs toxicology. Medical and environmental applications of the NSMs are discussed here. Also, key factors on the toxicity of the nanoparticles such as shape, size, chemical composition, and surface functionality are discussed. Finally, toxicity of the nanoparticles is going to be highlighted, and relevant studies are critically compared. This review gives a broad scientific view for improving the functional efficiency of nanomaterials while mitigating their possible adverse and unintended effects on biological systems.     

Density functional theory study of structural,electronic,and thermal properties of Pt,Pd, Rh,Ir, Os and PtPdX(X= Ir,Os, and Rh) alloys

The structural, electronic, mechanical, and thermal properties of Pt, Pd, Rh, Ir, Os metals and their alloys Pt Pd X(X= Ir, Os and Rh) are studied systematically using ab initio density functional theory. The groundstate properties such as lattice constant and bulk modulus are calculated to find the equilibrium atomic position for stable alloys. The electronic band structure and density of states are calculated to study the electronic behavior of metals on making their alloys. The electronic properties substantiate the metallic behavior for all studied materials. The firstprinciples density functional perturbation theory as implemented in quasi-harmonic approximation is used for the calculations of thermal properties.We have calculated the thermal properties such as the Debye temperature, vibrational energy, entropy and constant-volume specific heat. The calculated properties are compared with the previously reported experimental and theoretical data for metals and are found to be in good agreement. Calculated results for alloys could not be compared because there is no data available in the literature with such alloy composition.