Solid Support Material Research Articles

Bactericidal Hydrogels via Surface Functionalization with Cecropin A.

The immobilization of antimicrobial peptides (AMPs) to surfaces, enabling their utilization in biosensor and antibacterial/antifouling coating applications, is typically performed using rigid, solid support materials such as glass or gold and may require lengthy, temperamental protocols. Here, we employ a hydrogel immobilization platform to afford facile fabrication and surface functionalization while offering improved biocompatibility for evaluating the influence of linker length, surface density, and AMP conjugation site on retained peptide activity. Rapid, interfacial photo-polymerization using the radical-mediated thiol-ene addition mechanism was used to generate cross-linked, polymeric coatings bearing residual thiol moieties on prefabricated poly(ethylene glycol) (PEG)-based hydrogel supports. The photo-polymerized coatings were 60 μm thick and contained 0.55 nmol of unreacted free thiols, corresponding to a concentration of 410 μM, for use as cecropin A (CPA) immobilization handles via thiol-maleimide conjugation, where the CPA-bound maleimide moiety was localized at either the carboxyl terminus or midsequence between Ala22 and Gly23. Surface presentation of the thiol handles was controlled by varying the thiolated PEG monomer (PEGSH) used in the photo-polymerizable formulation. Bactericidal activity of CPA functionalized hydrogels against E. coli K235 indicated that CPA immobilized at the carboxyl terminus killed 94 ± 6% of the inoculated pathogens when coatings were prepared with high molecular weight PEGSH and 99 ± 1% when prepared with low molecular weight PEGSH. E. coli cell death demonstrated a stronger dependence on peptide concentration than PEG linker length or degree of thiol functionalization, with activity ranging from 34 ± 13% to 99 ± 1% bacterial cells killed as the prefunctionalization thiol concentration in the coatings was increased from 90 to 990 μM. Finally, the immobilization site on the surface-bound CPA strongly affected antibacterial activity; when midsequence modified CPA was bound to a hydrogel coating bearing 990 μM thiol, only 20 ± 4% of the E. coli population was killed.

Nickel electrodes as a cheap and versatile platform for studying structure and function of immobilized redox proteins

Practical use of many bioelectronic and bioanalytical devices is limited by the need of expensive materials and time consuming fabrication. Here we demonstrate the use of nickel electrodes as a simple and cheap solid support material for bioelectronic applications. The naturally nanostructured electrodes showed a surprisingly high electromagnetic surface enhancement upon light illumination such that immobilization and electron transfer reactions of the model redox proteins cytochrome b5 (Cyt b5) and cytochrome c (Cyt c) could be followed via surface enhanced resonance Raman spectroscopy. It could be shown that the nickel surface, when used as received, promotes a very efficient binding of the proteins upon preservation of their native structure. The immobilized redox proteins could efficiently exchange electrons with the electrode and could even act as an electron relay between the electrode and solubilized myoglobin. Our results open up new possibility for nickel electrodes as an exceptional good support for bioelectronic devices and biosensors on the one hand and for surface enhanced spectroscopic investigations on the other hand.

ChemInform Abstract: Fe3O4 (Iron Oxide)‐Supported Nanocatalysts: Synthesis, Characterization and Applications in Coupling Reactions

AbstractReview: 292 refs.

Innovative Graphite Oxide-Cellulose Based Material Specific for Genomic DNA Extraction

Extraction of genomic DNA from various types of samples is often challenging for commercial silica spin column. In this study, we proposed graphite oxide (GO)/cellulose composite as an alternative material for genomic DNA extraction. The purity of DNA and extraction efficiency were compared to that of commercial silica product. In this study, the total weight % of GO was fixed at 4.15% in GO/Cellulose composite. Chewed gum, nail clip, cigarette bud paper, animal tissue and hair sample were used as various genomic DNA sources for extraction experiments. Among all types of samples, the extraction efficiencies were 4 to 12 times higher than that of commercial silica spin column. The absorbance ratio of 260 nm to 280 nm (A260/A280) of all samples ranged between 1.6 and 2.0. The results demonstrated that GO/Cellulose composites might serve as an innovative solid support material for genomic DNA extraction.

Solid phase extraction using silica gel modified with azo-dyes derivative for preconcentration and separation of Th(IV) ions from aqueous solutions

Azo-dyes derivative (HL) sorbent was synthesized according to the literature to be used in the adsorption and preconcentration of Th(IV) ions from aqueous solution and it was exposed to immobilization, and new solid support material was obtained. For this purpose, azo-dyes derivative (HL) was chemically bonded to silica gel surface immobilized 3-chloropropyl trimethoxysilane, then analyzed by FTIR, BET, SEM and elemental analysis. The influence of the solution pH, initial Th(IV) concentration, amount of sorbent, contact time, temperature and foreign ion effect was investigated. The maximum Th(IV) uptake capacity was found to be 24.85 ± 0.2 mg/g.

Direct Synthesis of Hydrogen Peroxide from Hydrogen and Oxygen over Pd‐supported Metal‐Organic Framework Catalysts

Pd‐supported metal‐organic framework (MOF) catalysts have been applied for the direct synthesis of H2O2 from H2 and O2 under intrinsically safe and noncorrosive reaction conditions. The catalytic performance was strongly governed by the properties of the support materials, and the Brønsted acid sites newly introduced on the organic linkers of MOF were proven to be more effective than the Lewis acid sites on the open metal sites in enhancing the H2O2 formation and suppressing its decomposition. Pd/MIL‐101‐SO3H was highly efficient in promoting the reaction owing to the contribution from the strong acidity and highly porous nature of the robust MOF support used. The hydrogen peroxide productivity of Pd/MIL‐101‐SO3H catalyst reached 361 mmol H2O2 mmol/Pd/h, which was 2.3 or 1.7 times higher than that of the conventional Pd/HBEA (SAR = 25) or Pd/sulfonated resin catalyst, respectively. This result clearly demonstrates the promising potential of MOF as a solid acid support material.

<i>In-Situ</i> Hydroelectrothermal Deposition of Silicate Layers on Stainless Steel Surfaces

The deposition of zeolites on solid support materials is possible by means of electrochemical methods, impregnation processes, as well as in-situ syntheses. Electrochemical deposition of zeolites has been reported as well, however with readily synthesized zeolite structures. Adhesive deposition of zeolites on stainless steel (S316) has been reported. This report investigates the feasibility of the deposition of silicates by in-situ hydroelectrothermal means. The investigation was done in aqueous solutions of pH = 7 to 13 at different temperatures (25°C to 70°C) by linear sweep method. Deposition was done at a saturated H2 atmosphere to ensure prior deposition of thin iron oxide film on the surface and formation of Fe-O-Si-linkages. This was proven by Raman measurement of the samples. Further linear sweep experiments in the presence of silica show monodentate and bidentate Fe-O-Si linkages on the surface, proven by IR-measurements. Presence of dissolved silica was done by UV-Vis with the molybdate yellow method. The best results are achieved at 70°C at pH 13 and ﹣4 mV (vs Ag/AgCl) or 200 mV (vs SHE). Discontinuous homogeneous layers are found on the stainless steel surface observed by SEM, EDX measurements and electrochemical measurements. Layer discontinuties are caused due to low silica concentration at equilibrium hydrothermal conditions, especially in the absence of silicic acid. All results shown are for the best results achieved except for linear sweep measurements and solubility constants of dissolved silica.

Kinetics upon Isomerization of α,β-Pinene Oxides over Supported Ionic Liquid Catalysts Containing Lewis Acids

Wood extractives such as α-pinene oxide and β-pinene oxide are important renewable chemicals for the synthesis of fine chemicals, pharmaceuticals, and value-added intermediates. In this work, catalytic transformations of biomass derived extractives, isomerization of α,β-pinene oxides were studied over supported ionic liquid catalysts (SILCAs). SILCAs consist of catalytic species (e.g., metal nanoparticles or metal complexes) in a thin layer of ionic liquid which is immobilized on a solid support material (e.g., active carbon cloth). The reaction kinetics of the isomerization reactions over supported ionic liquid catalysts were studied and modeled. Mechanistic kinetic models describing the differences in selectivity and activity of the catalysts containing different ionic liquids were developed, and the models described the reaction rates and product distributions very well.

Isomerisation of α-Pinene Oxide to Campholenic Aldehyde Over Supported Ionic Liquid Catalysts (SILCAs)

The isomerisation of α-pinene oxide to campholenic aldehyde, an expensive ingredient utilized by e.g. flavor industry, was studied over Supported Ionic Liquid Catalysts (SILCAs) consisting of catalytically active species residing in ionic liquid. The ionic liquid, in turn, was immobilized on a solid support material. SILCAs were demonstrated as efficient catalysts for the transformation of α-pinene oxide into campholenic aldehyde, with the product distribution and activity being dependent on the nature of the ionic liquid.

Chemical modification of silica gel with synthesized Schiff base hydrazone derivative and application for preconcentration and separation of U(VI) ions from aqueous solutions

Schiff base hydrazone derivative (HL) sorbent was synthesized according to the literature to be used in the adsorption and preconcentration of U(VI) ions from aqueous solution and it was exposed to immobilization, and new solid support material was obtained. For this purpose, Schiff base hydrazone derivative (HL) was chemically bonded to silica gel surface immobilized 3-aminopropyl trimethoxysilane, then analyzed by Fourier transform infrared, Brunauer–Emmett–Teller, scanning electron microscopy and elemental analysis. The influence of the solution pH, amount of sorbent, contact time, temperature, foreign ion effect and initial U(VI) concentration was investigated. The maximum U(VI) uptake capacity was found to be 8.46 mg/g.

Synthesis, Solid‐State NMR Characterization, and Application for Hydrogenation Reactions of a Novel Wilkinson’s‐Type Immobilized Catalyst

Silica nanoparticles (SiNPs) were chosen as a solid support material for the immobilization of a new Wilkinson's-type catalyst. In a first step, polymer molecules (poly(triphenylphosphine)ethylene (PTPPE); 4-diphenylphosphine styrene as monomer) were grafted onto the silica nanoparticles by surface-initiated photoinferter-mediated polymerization (SI-PIMP). The catalyst was then created by binding rhodium (Rh) to the polymer side chains, with RhCl3⋅x H2O as a precursor. The triphenylphosphine units and rhodium as Rh(I) provide an environment to form Wilkinson's catalyst-like structures. Employing multinuclear ((31)P, (29)Si, and (13)C) solid-state NMR spectroscopy (SSNMR), the structure of the catalyst bound to the polymer and the intermediates of the grafting reaction have been characterized. Finally, first applications of this catalyst in hydrogenation reactions employing para-enriched hydrogen gas (PHIP experiments) and an assessment of its leaching properties are presented.

Using Ceriporiopsis subvermispora CZ-3 laccase for indigo carmine decolourization and denim bleaching

In this study, the production of laccase by Ceriporiopsis subvermispora CZ-3 has been studied under semi solid-state conditions using natural waste as solid support materials. Different concentrations of xylidine derivatives were also investigated as inducer affecting laccase production. Melon peel having the lowest C/N ratio in comparison to other supports led to the highest activity levels, reaching maximum values of about 3000 UL−1 for C. subvermispora CZ-3 in the presence of 2,4-xylidine. Laccase produced by this fungus was partially purified by ammonium sulphate precipitation and Sephacryl S-100 HR size exclusion chromatography. Several kinetic parameters of enzyme were also determined with 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonate) as a substrate. On the other hand, several compounds were investigated with respect to mediator effect for decolourization of indigo carmine and denim bleaching by this enzyme. It was observed that most of the compounds have mediator effect for decolourization of indigo carmine whereas 1-hydroxybenzotriazol is an appropriate compound for indigo dyed denim bleaching.

Metallocene Catalyzed Ethylene Polymerization with Specially Designed Catalyst Supports and Reaction Systems

SummaryIn heterogeneously catalyzed polymerization of α‐olefins, the characteristics of a solid support material impact the catalyst activity, polymer particle morphology, and resulting polymer properties. Silica is the most widely used support for metallocene catalysts in α‐olefin polymerization processes because of its large surface area and favorable surface properties for catalyst anchoring. Understanding the kinetics of heterogeneous olefin polymerization over a solid‐supported catalyst is often quite complicated because of mass transfer effects and catalyst particle fragmentation during the polymerization. Incomplete or premature fragmentation of support material results in a large fraction of catalyst sites left unavailable for the polymerization, causing some inconsistencies in the performance of the catalyst. Silica‐supported metallocene catalysts for α‐olefin polymerization are known to follow the layer‐by‐layer fragmentation mechanism where the fracture of the silica/polymer layer begins from the surface region of a silica particle and it gradually continues into the center of the particle as fragmentation is complete. In this paper, we present new experimental results on ethylene polymerization with rac‐Et(indenyl)2ZrCl2/MAO catalyst using different types of silica supports to quantitatively assess the effects of support geometry on intrinsic catalytic activity. Flat surface silica, nano‐sized spherical silica, straight cylindrical pore silica, and conventional silica are used as supports. The presence or absence of intraparticle monomer diffusion resistance and particle fragmentation has been shown to have significant effects on the catalytic activity.

Influence of Solid Supports on Acyl Migration in 2‐Monoacylglycerols: Purification of 2‐MAG via Flash Chromatography

AbstractSoybean oil 2‐monoacylglycerol (2‐MAG) was synthesized via the Novozym 435‐catalyzed ethanolysis of triacylglycerols and purified by conventional liquid–liquid extraction. The 2‐MAG was subjected to incubation at 20 and 40 °C in the presence of five solid commercial support materials, Lewatit, Silica Gel 60, Alumina–Neutral Brockman Activity 1, Amberlyst‐15, and SBA‐15, to determine their effects on acyl migration rates. Lewatit and SBA‐15 did not catalyze acyl migration rates after 144 h, while silica gel slightly increased migration rates. The more polar alumina and the cationic Amberlyst 15 significantly increased migration rates. Flash chromatography purification of 2‐MAG using silica gel as the immobile phase developed with an acetone/hexane binary gradient proved to be a comparable purification method to liquid–liquid extraction, resulting in 60 % 2‐MAG yield, no residual triacylglycerol, diacylglycerol, or glycerol co‐products, and a 95 mol% 2‐MAG purity vs. 1‐MAG, demonstrating that flash chromatography did not catalyze acyl migration.

Catalytic oxidation of thioanisole using oxovanadium(IV)‐functionalized electrospun polybenzimidazole nanofibers

AbstractPolybenzimidazole fibers, with an average diameter of 262 nm, were produced by the process of electrospinning. These fibers were used as a solid support material for the immobilization of oxovanadium(IV) which was achieved via a reaction with vanadyl sulfate. The oxovanadium(IV)‐functionalized nanofibers were used as heterogeneous catalysts for the oxidation of thioanisole under both batch and pseudo‐continuous flow conditions with great success. Under batch conditions near quantitative oxidation of thioanisole was achieved in under 90 min, even after four successive catalytic reactions. Under continuous conditions, excellent conversion of thioanisole was maintained throughout the period studied at flow rates of up to 2 mLh−1. This study, therefore, proposes that electrospun polybenzimidazole nanofibers, with their small diameters, impressive chemical and thermal stability, as well as coordinating benzimidazole group, may be a desirable support material for immobilization of homogeneous catalysts. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Low melting Li/K/Cs acetate salt mixtures as new ionic media for catalytic applications – first physico-chemical characterization

In order to expand the temperature limits of Supported Ionic Liquid Phase (SILP) or Solid Catalyst with Ionic Liquid Layer (SCILL) systems to higher operation temperatures, the mixture of lithium acetate, potassium acetate, and caesium acetate (molar ratio of 0.2/0.275/0.525) has been studied in detail. Physico-chemical properties of the bulk melt are reported together with stability data of the modern salt on various solid support materials showing attractive properties for many potential high temperature applications.

New strategies in sample clean-up for mycotoxin analysis

So far, solid phase extraction, the use of MycoSep columns and immunoaffinity chromatography are the most common clean-up methods in mycotoxin analysis. Among these methods, immunoaffinity chromatography offers the highest selectivity and therefore the highest efficiency in removing interfering matrix compounds and enriching the analyte. Common immunoaffinity columns are prepared by covalently binding the antibodies to a solid support material which, due to the harsh conditions applied, frequently lowers their affinity for the antigen. The review article presents new strategies which have been developed to overcome this problem: sol-gel immunoaffinity chromatography, immuno-ultrafiltration, the use of aptamers as selective ligands and the application of molecularly imprinted polymers. The present paper covers the principles as well as the application of these approaches for sample clean-up in mycotoxin analysis.

Chromatographic separation of carrier free 90Y from 90Sr using a diglycolamide based resin for possible pharmaceutical applications

N,N,N′,N′-tetraoctyl diglycolamide (TODGA) has been used as the stationary phase in an extraction chromatography resin (XCR) material prepared for evaluating the uptake and the separation behaviour of 90Y and 90Sr from acidic feeds. Chromosorb-W was used as the solid support material while the feed solution was usually 4 M HNO 3. The batch uptake studies have suggested almost no Sr(II) uptake while Y(III) uptake increased with acidity up to 4 M HNO 3 beyond which a decrease in the K d,w values were observed. Column studies were carried out and breakthrough profiles were obtained for both Y(III) and Sr(II). No breakthrough of Y(III) was noticed even when >50 column volumes of the feed (carrier free 90Y at 4 M HNO 3) was passed through the column while about 20 column volumes were required for the breakthrough of Y(III) when the feed contained 1 g/L Y in 4 M HNO 3 spiked with 90Y tracer. The reusability of the column was also studied which indicated in the deterioration of the column performance as shown by the sharp fall in the breakthrough volumes and was attributed to the probable leaching of the reagent from the support material. The role of absorbed dose was also investigated for Y(III) uptake. Separation of carrier free 90Y tracer was carried out by loading the column with 90Sr and eluting with 0.01 M solutions of HNO 3 as well as EDTA. The purity of the product was ascertained by half-life method.

Die Realisierung von anatomischen Felsenbeinfaksimilemodellen mit cochleären Hohlraumstrukturen

Microsurgical dissection exercises are essential in otosurgery training. Human temporal bone specimens are rarely available for necessary extensive preparation steps up to the cochlea. This requires the development of new Anatomical Facsimile Models (AFM) of the temporal bone with its diffizil internal structures. The construction of AFM was realized by rapid prototyping technologies. Data for processing come from high resolution CT-scans. With the production of AFM true to the original structures of the temporal bone by rapid prototyping methods it was possible to reproduce the very small cavity structures of the inner ear (cochlea, semicircular canals). All cavity structures of the temporal bone, including the middle ear, are constructed without solid support material. This allows the introduction of Cochlea-Implant electrodes into the cochlea. The use of modern rapid prototyping technologies enables us to produce any number of identical models of an original specimen. The preparation steps and the material properties correspond to those of the original temporal bone. Therefore AFM are excellent preparation models.

Matrix Solid-Phase Dispersion Extraction and Capillary Electrophoresis Determination of Tetracycline Residues in Milk

A capillary zone electrophoresis method was proposed for simultaneous detection and quantification of three tetracycline antibiotics in commercial milk samples, i.e., tetracycline, oxytetracycline, and doxycycline. The influences of the electrolyte composition, pH, as well as temperature and applied voltage on separation were investigated. The optimal running buffer was 30 mM Na2HPO4 and 1 mM EDTA at pH 11.5, with 3 s hydrodynamic injection, 25 kV applied voltage, and UV detection at 268 nm. Matrix solid-phase dispersion procedure was used for sample pretreatment. Several solid support materials were investigated, and silica with bonded C18 chains (C18) was used as sorbent. Electrophoretic analysis was completed in less than 6 min, with LODs ranging from 0.0745 μg/mL for oxytetracycline to 0.0808 μg/mL for doxycycline. The recoveries obtained were between 93.4% and 102%.