Mesoporous silica-immobilized aluminium chloride as a new catalyst system for the isopropylation of naphthalene

Mesoporous MCM-41 silica immobilized aluminium chloride shows high catalytic activity and selectivity in the Friedel-Crafts alkylation of naphthalene with isopropanol.

Ironporphyrin immobilized onto montmorillonite as a bimimetical model for azo dye oxidation

In this work, we studied the oxidation of the azo dye Disperse orange 3 (DO3) by hydrogen peroxide, catalyzed by 5,10,15, 20-tetrakis(4-N-methylpyridyl)porphyrin iron(III) chloride immobilized onto montmorillonite K10, FeP-K10. Results showed that the FeP-K10/H2O2 system is efficient for discoloration of the DO3 dye, especially at pH 3.0. The catalyst was shown to be relatively stable and could be recycled many times, leading to good yields. DO3 oxidation products were analyzed by gas chromatography and mass spectrometry, being 4-nitroaniline the main product. Tert-butylhydroperoxide and iodosylbenzene were also used as oxidants, giving rise to 4-nitroaniline as product too. The studied system is a good biomimetic model of oxidative enzymes, being a promising discoloring agent for azo dyes. (C) 2007 Elsevier Ltd. All rights reserved.

Jacobsen catalyst immobilized on chitosan membrane as interface catalyst in organic/aqueous system for alkene oxidation

The Jacobsen catalyst, Mn(salen), was immobilized in chitosan membrane. The obtained Mn(salen)-Chit was characterized by thermogravimetric analysis (TC), differential thermal analysis (DTA), differential scanning calorimetry (DSC), infrared spectroscopy (FT-IR), degree of N-acetylation by (1)H NMR, and UV-vis spectroscopy. The UV-vis absorption spectrum of the encapsulated catalyst displayed the typical bands of the Jacobsen catalyst, and the FT-IR presented an absorption band characteristic of the imines present in the Jacobsen catalyst. The chitosan membranes were available, in a biphasic system, as a catalytic barrier between two different phases: an organic substrate phase (cyclooctene or styrene) and an aqueous solution of either m-CPBA, t-BuOOH or H(2)O(2), and dismissing the need for phase transfer agents and leading to better product yields compared with the catalyst in homogeneous medium. This new catalyst did not leach from the support and was reused many times, leading to high turnover frequencies. (C) 2009 Elsevier B.V. All rights reserved.

Degradation of phenanthrene and pyrene in soil slurry reactors with immobilized bacteria Zoogloea sp.

The environmental fate of polycyclic aromatic hydrocarbons (PAHs) in soils is motivated by their wide distribution, high persistence, and potentially deleterious effect on human health. Polycyclic aromatic hydrocarbons constitute the largest group of environmental contaminants released in the environment. Therefore, the potential biodegradation of these compounds is of vital importance. A biocarrier suitable for the colonization by micro-organisms for the purpose of purifying soil contaminated by polycyclic aromatic hydrocarbons was developed. The optimized composition of the biocarrier was polyvinyl alcohol (PVA) 10%, sodium alginate (SA) 0.5%, and powdered activated carbon (PAC) 5%. There was no observable cytotoxicity of biocarriers on immobilized cells and a viable cell population of 1.86 x 10(10) g(-1) was maintained for immobilized bacterium. Biocarriers made from chemical methods had a higher biodegradation but lower mechanical strengths. Immobilized bacterium Zoogloea sp. had an ideal capability of biodegradation for phenanthrene and pyrene over a relative wide concentration range. The study results showed that the biodegradation of phenanthrene and pyrene reached 87.0 and 75.4%, respectively, by using the optimal immobilized method of Zoogloea sp. cultivated in a sterilized soil. Immobilized Zoogloea sp. was found to be effective for biodegrading the soil contaminated with phenanthrene and pyrene. Even in natural (unsterilized) soil, the biodegradation of phenanthrene and pyrene using immobilized Zoogloea sp. reached 85.0 and 67.1%, respectively, after 168 h of cultivation, more than twice that achieved if the cells were not immobilized on the biocarrier. Therefore, the immobilization technology enhanced the competitive ability of introduced micro-organisms and represents an effective method for the biotreatment of soil contaminated with phenanthrene and pyrene.

Electrocardiographic parameters of captive lions (Panthera leo) and tigers (Panthera tigris) immobilized with ketamine plus xylazine

Twenty-seven healthy captive lions (Panthera leo) and 13 healthy captive tigers (Panthera tigris) from S to Paulo Zoo (Fundacao Parque Zoologico de Rio Paulo, Sao Paulo, Brazil) collection were selected for this study. They were anesthetized with ketamine (10 mg/kg) combined with xylazine (1-2 mg/kg) for physical examinations. hematologic and serum chemical analysis and electrocardiogram recording. The main aim of this research was to gather initial information about normal electrocardiographic parameters of large felids. Standard P-QRS-T deflections on leads described for domestic carnivores were analyzed, and they did not greatly differ from those of large felids. taking into account the greater weight and corporal mass of large felids. Heart rate of lions ranged frorn 42 to 76 beats per minute (bpm). Heart rate of tigers ranged from 56 to 97 bpm. In both species, the most common rhythm detected was normal sinus rhythm followed by sinus arrhythmia: wandering, pacemaker was also observed with normal sinus rhythm or sinus arrhythmia. Mean electrical axis lay between +60 degrees and +120 degrees. QRS complexes were predominantly positive in leads DI, DII, DIII, and AVF and negative in AVR and AVL. This Study provides insights into normal electrocardiograms of large felids. Wider investigations on the same subject arc necessary to establish criteria for the recognition of abnormalities in these species and should include other anesthetic drug(s) combinations and reports of electrocardiographic features of animals with cardiac disease and electrolytes disturbances.

Bioconversion of D-glucose into D-glucosone by immobilized glucose 2-oxidase from Coriolus versicolorat moderate pressures

The immobilized glucose 2-oxidase (pyranose oxidase, pyranose:oxygen-2-oxidoreductase, EC 1.1.3.10) from Coriolus versicolor was used to convert D-glucose into D-glucosone at moderate pressures, up to 150 bar, with compressed air in a modified commercial batch reactor. Several parameters affecting biocatalysis at moderate pressures were investigated as follows: pressure, different forms of immobilized biocatalysts, glucose concentration, pH, temperature and the presence of catalase. Glucose 2-oxidase (GOX2) was purified by immobilized metal affinity chromatography on epoxy-activated Sepharose 6B-IDA-Cu(II) column at pH 6.0. Purified enzyme and catalase were immobilized into a polyethersulfone (PES) membrane in the presence of glutaraldehyde and gelatin. Enhancement of the bioconversion of D-glucose was done by the pressure since an increase in the pressure with compressed air increases the conversion rates. The optimum temperature and pH for bioconversion of D-glucose were found to be 62 degrees C and pH 6.0, respectively and the activation energy (E(a)) was 28.01 kJ mol(-1). The apparent kinetic constants (V(max)' K(m)', K(cat)' and K(cat)/K(m)') for this bioconversion were 2.27 U mg(-1) protein, 11.15 mM, 8.33 s(-1) and 747.38 s(-1) M(-1), respectively. The immobilized biomass of C. versicolor as well as crude extract containing GOX2 activity were also useful for bioconversion of D-glucose at 65 bar with a yield of 69.9 +/- 3.8% and 91.3 +/- 1.2%, respectively. The immobilized enzyme was apparently stable for several months without any significant loss of enzyme activity. On the other hand, this immobilized enzyme was also stable at moderate pressures, since such pressures did not affect significantly the enzyme activity. (C) 2010 Elsevier Ltd. All rights reserved.

Chromatographic behaviour of monoclonal antibodies against wild-type amidase from Pseudomonasaeruginosa on immobilized metal chelates

The aim of this work was to devise a one-step purification procedure for monoclonal antibodies (MAbs) of IgG class by immobilized metal affinity chromatography (IMAC). Therefore, several stationary phases were prepared containing immobilized metal chelates in order to study the chromatographic behaviour of MAbs against wild-type amidase from Pseudomonas aeruginosa. Such MAbs adsorbed to Cu(II), Ni(II), Zn(II) and Co(II)-IDA agarose columns. The increase in ligand concentration and the use of longer spacer arms and higher pH values resulted in higher adsorption of MAbs into immobilized metal chelates. The dynamic binding capacity and the maximum binding capacity were 1.33 +/- 0.015 and 3.214 +/- 0.021 mg IgG/mL of sedimented commercial matrix, respectively. A K(D) of 4.53 x 10(-7) M was obtained from batch isotherm measurements. The combination of tailor-made stationary phases of IMAC and the correct selection of adsorption conditions permitted a one-step purification procedure to be devised for MAbs of IgG class. Culture supernatants containing MAbs were purified by IMAC on commercial-Zn(II) and EPI-30-IDA-Zn(II) Sepharose 6B columns and by affinity chromatography on Protein A-Sepharose CL-4B. This MAb preparation revealed on SDS-PAGE two protein bands with M(r) of 50 and 22 kDa corresponding to the heavy and light chains, respectively. Copyright (C) 2011 John Wiley & Sons, Ltd.

Copper(II) aza-bis(oxazoline) complex immobilized onto ITQ-2 and MCM-22 based materials as heterogeneous catalysts for the cyclopropanation of styrene

A copper(II) chiral aza-bis(oxazoline) homogeneous catalyst (CuazaBox) was anchored onto the external surface of MCM-22 and ITQ-2 structures, as well as encapsulated into hierarchical MCM-22. The transition metal complex loading onto the porous solids was determined by ICP-AES and the materials were also characterized by elemental analysis (C, N, H, S), FTIR, XPS, TG and low temperature N-2 adsorption isotherms. The materials were tested as heterogeneous catalysts in the benchmark reaction of cyclopropanation of styrene to check the effect of the immobilization procedure on the catalytic parameters, as well as on their reutilization in several catalytic cycles. Catalyst CuazaBox anchored onto the external surface of MCM-22 and ITQ-2 materials were more active and enantioselective in the cyclopropanation of styrene than the corresponding homogeneous phase reaction run under similar experimental conditions. This is due to the propylation of the acidic aza-Box nitrogen. HMCM-22 was nevertheless the best heterogeneous catalyst. Encapsulation of CuazaBox on post-synthesis modified MCM-22 materials led to low activities and enantioselectivities. But reversal on the stereochemical course of the reaction was observed, probably due to confinement effect. (C) 2013 Elsevier Inc. All rights reserved.

Production of hydroxamic acids by immobilized Pseudomonas aeruginosa cells Kinetic analysis in reverse micelles

Intact cells from Pseudomonas aeruginosa strain L10 containing amidase were used as biocatalysts both free and immobilized in a reverse micellar system. The apparent kinetic constants for the transamidation reaction in hydroxamic acids synthesis, were determined using substrates such as aliphatic, amino acid and aromatic amides and esters, in both media. In reverse micelles, K-m values decreased 2-7 fold relatively to the free biocatalyst using as substrates acetamide, acrylamide, propionamide and glycinamide ethyl ester. We have concluded that overall the affinity of the biocatalyst to each substrate increases when reactions are performed in the reversed micellar system as opposed to the buffer system. The immobilized biocatalyst in general, exhibits higher stability and faster rates of reactions at lower substrates concentration relatively to the free form, which is advantageous. Additionally, the immobilization revealed to be suitable for obtaining the highest yields of hydroxamic acids derivatives, in some cases higher than 80%. (C) 2013 Elsevier B.V. All rights reserved.

Efficient cyclohexane oxidation with hydrogen peroxide catalysed by a C-scorpionate iron(II) complex immobilized on desilicated MOR zeolite

The hydrotris(pyrazol-1-yl)methane iron(II) complex [FeCl2{eta(3)-HC(pz)(3)}] (Fe, pz = pyrazol-1-yl) immobilized on commercial (MOR) or desilicated (MOR-D) zeolite, catalyses the oxidation of cyclohexane with hydrogen peroxide to cyclohexanol and cyclohexanone, under mild conditions. MOR-D/Fe (desilicated zeolite supported [FeCl2{eta(3)-HC(pz)(3)}] complex) provides an outstanding catalytic activity (TON up to 2.90 x 10(3)) with the concomitant overall yield of 38%, and can be easy recovered and reused. The MOR or MOR-D supported hydrotris(pyrazol-1-yl)methane iron(II) complex (MOR/Fe and MOR-D/Fe, respectively) was characterized by X-ray powder diffraction, ICP-AES, and TEM studies as well as by IR spectroscopy and N-2 adsorption at -196 degrees C. The catalytic operational conditions (e.g., reaction time, type and amount of oxidant, presence of acid and type of solvent) were optimized. (C) 2013 Elsevier B.V. All rights reserved.

Electroanalysis of urinary L-dopa using tyrosinase immobilized on gold nanoelectrode ensembles

The performance of an amperometric biosensor constructed by associating tyrosinase (Tyr) enzyme with the advantages of a 3D gold nanoelectrode ensemble (GNEE) is evaluated in a flow-injection analysis (FIA) system for the analysis of l-dopa. GNEEs were fabricated by electroless deposition of the metal within the pores of polycarbonate track-etched membranes. A simple solvent etching procedure based on the solubility of polycarbonate membranes is adopted for the fabrication of the 3D GNEE. Afterward, enzyme was immobilized onto preformed self-assembled monolayers of cysteamine on the 3D GNEEs (GNEE-Tyr) via cross-linking with glutaraldehyde. The experimental conditions of the FIA system, such as the detection potential (−0.200 V vs. Ag/AgCl) and flow rates (1.0 mL min−1) were optimized. Analytical responses for l-dopa were obtained in a wide concentration range between 1 × 10−8 mol L−1 and 1 × 10−2 mol L−1. The limit of quantification was found to be 1 × 10−8 mol L−1 with a resultant % RSD of 7.23% (n = 5). The limit of detection was found to be 1 × 10−9 mol L−1 (S/N = 3). The common interfering compounds, namely glucose (10 mmol L−1), ascorbic acid (10 mmol L−1), and urea (10 mmol L−1), were studied. The recovery of l-dopa (1 × 10−7 mol L−1) from spiked urine samples was found to be 96%. Therefore, the developed method is adequate to be applied in the clinical analysis.

Non-enzymatic assay for glucose by using immobilized whole-cells of E. coli containing glucose binding protein fused to fluorescent proteins

Glucose monitoring in vivo is a crucial issue for gaining new understanding of diabetes. Glucose binding protein (GBP) fused to two fluorescent indicator proteins (FLIP) was used in the present study such as FLIP-glu- 3.2 mM. Recombinant Escherichia coli whole-cells containing genetically encoded nanosensors as well as cell-free extracts were immobilized either on inner epidermis of onion bulb scale or on 96-well microtiter plates in the presence of glutaraldehyde. Glucose monitoring was carried out by Förster Resonance Energy Transfer (FRET) analysis due the cyano and yellow fluorescent proteins (ECFP and EYFP) immobilized in both these supports. The recovery of these immobilized FLIP nanosensors compared with the free whole-cells and cell-free extract was in the range of 50–90%. Moreover, the data revealed that these FLIP nanosensors can be immobilized in such solid supports with retention of their biological activity. Glucose assay was devised by FRET analysis by using these nanosensors in real samples which detected glucose in the linear range of 0–24 mM with a limit of detection of 0.11 mM glucose. On the other hand, storage and operational stability studies revealed that they are very stable and can be re-used several times (i.e. at least 20 times) without any significant loss of FRET signal. To author's knowledge, this is the first report on the use of such immobilization supports for whole-cells and cell-free extract containing FLIP nanosensor for glucose assay. On the other hand, this is a novel and cheap high throughput method for glucose assay.

Cleusonite, (Pb,Sr)(U4+,U6+)(Fe2+ Zn)2(Ti,Fe2+ Fe3+)18(O,OH)38, a new mineral species of the crichtonite group from the western Swiss Alps

Cleusonite, (Pb,Sr)(U4+,U6+) (Fe2+,Zn)(2) (Ti,Fe2+,Fe3+)(18) (O,OH)(38), is a new member of the crichtonite group. It was found at two occurrences in greenschist facies metamorphosed gneissic series of the Mont Fort and Siviez-Mischabel Nappes in Valais, Switzerland (Cleuson and Bella Tolla summit), and named after the type locality. It occurs as black opaque cm-sized tabular crystals with a bright sub-metallic lustre. The crystals consist of multiple rhombohedra and hexagonal prisms that are generally twinned. Measured density is 4.74(4) g/cm(3) and can be corrected to 4.93(12) g/cm(3) for macroscopic swelling due to radiation damage; the calculated density varies from 5.02(6) (untreated) to 5.27(5) (heat-treated crystals); the difference is related to the cell swelling due to the metamictisation. The empirical formula for cleusonite from Cleuson is (Pb0.89Sr0.12)(Sigma=1.01) (U0.79+4U0.30+6)(Sigma=1.09) (Fe1.91+2Zn0.09)(Sigma=2.00) (Ti11.80Fe3.44+2Fe2.33+3V0.19+5Mn0.08Al0.07)(Sigma=17.90) [O-35.37(OH)(2.63)](Sigma=38). Cations were measured by electron microprobe, the presence of structural (OH) was confirmed by infrared spectroscopy and the U6+/U4+ and Fe2+/Fe3+ ratios were determined by X-ray photoelectron spectroscopy. Cleusonite is partly metamict, and untreated crystals only show three major X-ray diffraction peaks. Because of this radiation-damaged state, the mineral appears optically isotropic and shows a light-grey to white colour in reflected polarized light. Cleusonite is trigonal, space group R $(3) over bar $, and unit-cell parameters are varying from a = 10.576(3), c = 21.325(5) angstrom (untreated crystal) to a = 10.4188(6), c = 20.942(1) angstrom (800 degrees C treatment) and to a = 10.385(2), c = 20.900(7) angstrom (1000 degrees C treatment). The three cells give a common axial ratio 2.01 (1), which is identical to the measured morphological one 2.04(6). ne name cleusonite also applies to the previously described ``uranium-rich senaite'' from Alinci (Macedonia) and the ``plumbodavidite'' from Huanglongpu (China).

Isoelectric focusing of alpha-1 acid glycoprotein (orosomucoid) in immobilized pH-gradients with 8M urea: detection of its desialylated variants using an alkaline phosphatase-linked secondary antibody system.

A method allowing a clear separation of the different variants of desialylated alpha 1-acid glycoprotein (orosomucoid) has been developed using isoelectric focusing in immobilized pH gradients, supplemented with 8 M urea and 2% v/v 2-mercaptoethanol. Immunoblotting with two antibody-steps afforded high sensitivity and permitted the detection of about 700 pg of alpha 1-acid glycoprotein in a 20 microL plasma sample diluted 1:28 672. A one year old bloodstrain, kept at room temperature, could easily be phenotyped.