Tris Solution Research Articles

Deposition of indium oxide thin films assisted by gold nanoparticles in cyclohexane

Pulsed 532-nm light from a Q-switched neodymium: yttrium aluminum garnet (Nd:YAG) laser was used for depositing indium oxide (In 2O 3) films on a glass substrate immersed in a cyclohexane solution of gold nanoparticles and tris(2,4-pentanedionato)indium (In(pen) 3). The photoinduced deposition was triggered by photoabsorption of the gold nanoparticles. The deposited In(pen) 3 was sintered into semi-transparent and electroconductive In 2O 3 films by successive pulsed-laser irradiation. We demonstrated a one-pot single-step method to prepare electroconductive In 2O 3 films in a laser-irradiated area of the substrate.

Bio-friendly Synthesis of ZnO Nanoparticles in Aqueous Solution at Near-Neutral pH and Low Temperature

ZnO nanoparticles are synthesized using a new bio-friendly method. The experimental conditions are very mild: aqueous solution at near-neutral pH and 37 degrees C. The as-obtained nanoparticles show the stable wurtzite structure without the need of annealing. The two reagents used are aqueous solutions of zinc nitrate and buffer tris(hydroxymethyl)aminomethane. This is a standard nontoxic buffer and inert to a wide variety of chemicals and biomolecules, therefore extremely satisfactory for biochemical reactions. Furthermore, this is a polydentade ligand which adsorbs strongly on one or more surfaces of ZnO inhibiting its crystal growth and yielding nearly spherical ZnO nanoparticles. Our objective is to use the crystallization method described here for further incorporation of biomolecules as additives in the reaction solution, aiming at the formation of ZnO with new physical properties.

Surface Molecularly Imprinted TiO2 Nanoparticle for Photoreduction of Viologen

ABSTRACTWhen small organic molecules (e.g. amino acids, nucleotides, and so on) are incorporated in metal oxide particles formed from metal alkoxide in the sol-gel process, the organic moieties can be removed readily by solvent washing or by degradative oxidation. Under proper conditions, nano-sized cavities corresponding to the shape of the individual organic moiety are produced within the metal oxide network as molecularly imprinted material such as surface molecularly imprinted TiO2. We tried to fabricate nano-sized particle of TiO2 to increase the effective contact area for the reactants, and further additional function for molecular recognition was intended to introduce through the surface modification of the molecular imprinting method in order to enhance the photoreduction of viologen. In this context, we prepared viologen imprinted TiO2 as an active and stable photocatalyst for photoreduction of viologen as a well-defined and readily identifiable and reversible electron carrier with appropriate redox potential for photoactivated TiO2. The basic concept of molecularly imprinting in this system is as follows. Oxidized viologen is generally twisted and dication molecule. While, reduced viologen is planar and monocation radical. Once TiO2 has such recognition site on its surface, it would be distinguishable through shape or charge recognition or both factors and facilitate the inclusion or exclusion of the target molecule result the enhancement of the reduction. After the preparation of the template, sol-gel imprinting was performed. Measuring its dynamic light scattering monitored changes of the particle sizes and the diameter was stabilized ca 120 nm after 1 week stirring. X-ray diffraction pattern of the TiO2 powder after the dryness without calcination indicates the dominant peak for anatase. Removal of the template was almost 36% after the alkaline rinsing by measuring its UV vis spectra of the washings. A buffered solution of Tris including viologen was irradiated through a xenon lamp under stirring in a quartz cuvett in Ar with or without the TiO2 with cut-off filter at room temperature. The formation of viologen monocation radical whose color is blue was easily recognized only in the reaction with TiO2. The formation of viologen monocation radicals from three types of (methyl, hexyl, and pentacarboxyl) viologens with time in the presence of the imprinted TiO2 and blank one was monitored spectrophotometrically. Blank means that it was fabricated similar way to the imprinted one without the template. Among these results, aliphatic C6 side chains of bipyridinium and terminal carboxyl groups were not effective to enhance. On the other hand, the less bulkiness methyl viologen resulted the highest yield. The most important result is that higher conversion was observed in every case of imprinted TiO2 compared with blank one. Therefore, the key point for recognition is not peripheral part, but bipyridinium part of the viologen.

A novel strategy forab initiostructure determination using micro-powder X-ray diffraction: structure solution and refinement of 3-bromophenylboronic acid and tris(4-bromophenyl)boroxine

Micro-powder X-ray diffraction patterns of two compounds, namely 3-bromophenylboronic acid and tris(4-bromophenyl)boroxine, were recorded with microgram quantities of sample using a recently developed method employing nylon loops with synchrotron radiation and an image-plate detector. This method, besides using small amount of samples, offers the advantage of recording the powder pattern in the shortest possible time (less than a minute). The structures of the two compounds have been solved byab initiomethods using real-space techniques (simulated annealing and/or parallel tempering) followed by Rietveld refinements with soft restraints on the bond lengths of the rigid bodies. The former compound crystallizes in the monoclinic system [a= 15.7797 (4),b= 5.3085 (2),c= 9.3757 (3) Å, β = 93.357 (3)°; space groupP21/c;Z= 4;Rp= 16.060,Rwp= 10.543,RB= 4.25] with sheets of individual molecules linked through an extended hydrogen-bonding network. Tris(4-bromophenyl)boroxine, displaying molecular disorder, crystallizes in the orthorhombic system [a= 18.9289 (6),b= 21.8872 (6),c= 4.8842 (2) Å; space groupPnma;Z= 4;Rp= 13.270,Rwp= 12.083,RB= 6.06], with discrete molecules held by weak van der Waals forces in a zigzag fashion. It is believed that this is the first time that powder X-ray diffraction patterns using microgram samples have been successfully employed for the structure solution and refinement of molecules with reasonable complexity.

Layer-by-Layer Fabrication and Characterization of DNA-Wrapped Single-Walled Carbon Nanotube Particles

Carbon nanotubes have been proposed as support materials for numerous applications, including the development of DNA sensors. One of the challenges is the immobilization of DNA or other biological molecules on the sidewall of carbon nanotubes. This paper introduces a new fabrication of DNA-carbon nanotubes particles using the layer-by-layer (LBL) technique on single-walled carbon nanotubes (SWCNTs). Poly(diallyldimethylammonium) (PDDA), a positively charged polyelectrolyte, and DNA as a negatively charged counterpart macromolecule are alternatively deposited on the water-soluble oxidized SWCNTs. Pure DNA/PDDA/SWCNTs particles can be prepared and separated by simple unltracentrifugation. The characterization of DNA/PDDA/SWCNTs particles was carried out by scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-visible spectroscopy, Raman spectroscopy, and thermogravimetric analysis (TGA). An electrode modified by the DNA/PDDA/SWCNTs particles shows a dramatic change of the electrochemical signal in solutions of tris(2,2'-bipyridyl)ruthenium(II) ((Ru(bpy)(3)2+) as a reporting redox probe. A preliminary application of the DNA-modified carbon nanotubes in the development of DNA sensors used in the investigation of DNA damage by nitric oxide is presented.

Synthesis, Spectral Properties, and Antitumor Activity of a New Axially Substituted Phthalocyanine Complex of Zirconium(IV) with Citric Acid

The new axially substituted phthalocyanine (pc) complex of zirconium(IV) with citric acid is reported. It has been shown that the replacement of two Cl-atoms with two citric acid fragments takes place as the result of the reaction between [ZrCl2(pc)] and citric acid. The complex [Zr(citrate)2(pc)] was formed. The spectroscopic properties of the synthesized compound in DMSO, RPMI 1640 medium with and without fetal calf serum (FCS), H2O, and buffer (Tris) solutions have been described. Antitumor activity of this compound has been studied. The cytostatic activity was observed in the concentration range of 6.1-9.0x10(9) molecules [Zr(citrate)2(pc)]/cell and occurred in 4-6 h after treatment with [Zr(citrate)2(pc)] solution.

Synthesis, Structure, and Methyl Methacrylate Polymerization Activity of a Mixed π-Ferrocene π-Toluene Complex of Potassium Tris(hexamethyldisilazide)magnesiate

Treating a toluene solution of mixed potassium-magnesium tris(hexamethyldisilazide) with ferrocene yields a surprising complex exhibiting simultaneous arene and metallocene -coordination of K+, which when prepared in situ initiates the polymerization of MMA to give syndio-rich PMMA.

Solvothermal Synthesis, Crystal Structure, and Properties of the First Zinc Containing Thioantimonate(III) [Zn( tren )] 2 Sb 4 S 8 �0.75 H 2 O

Yellow crystals of the title compound were obtained under solvothermal conditions reacting elemental Zn, Sb, and S in a solution of tris(2-aminoethyl)amine (= tren) and water. The compound crystallises in the monoclinic space group P21/c with a=13.0247(7), b=22.308(2), c=12.1776(6) A, and β=105.352(6)°. In the structure of [Zn(tren)]2Sb4S8·0.75 H2O two [Zn(tren)]2+ cations are bound to the [Sb4S8]4− anion via S atoms. The Zn2+ ions are in a trigonal bipyramidal environment of four N atoms of the tetradentate tren ligand and one S atom of the [Sb4S8]4− anion. The anion is formed by SbS3 and SbS4 units which share common corners and edges. The interconnection mode yields three different non-planar Sb2S2 heterorings. The shortest intermolecular Sb–S distance amounts to about 3.7 A, and taking this long separation into account undulated chains running along [001] are formed with the water molecules residing in the pocket-like cavities. Upon heating the compound decomposes in one step starting at about 240°C. The final decomposition product was identified as ZnS and Sb2S3 by X-ray powder diffractometry. Additionally, spectroscopic data as well as synthetic procedures for [Zn(tren)]2Sb4S8·0.75 H2O are reported.

HPLC simultaneous analysis of thiols and disulfides: on-line reduction and indirect fluorescence detection without derivatization.

A liquid chromatography method with indirect fluorescence detection has been developed for simultaneous detection of cysteine, cystine, homocysteine, homocystine, glutathione and glutathione disulfide. After separation in their native forms, a post-column solution of tris(2-carboxyethyl)phosphine (TCEP) at 32 mM, pH 8 is added to reduce the disulfides on-line to the corresponding thiol. The effluent is then merged with a second post-column solution of the highly fluorescent complex Cd(HQS)(2)(2-). The cadmium is complexed by the eluting thiols, effectively quenching the fluorescence. Optimization of the separation, the on-line reduction and the indirect fluorescence detection are discussed. Detection limits from 0.3-4.3 microM (0.04 to 2.6 ppm) are achieved for the six analytes in a 20 min separation.

Formation of iron dispersed graphite composites utilizing exfoliated graphite and their magnetic properties

An organic solution of tris (acetylacetonato) iron (III) was impregnated by sorption into exfoliated graphite and dried at 180°C in air. By 1h treatment of this precursor at 900-1200°C in Ar (heating rate to each temperature: 400Kh-1), iron/graphite composites containing 33mass% Fe were obtained. In these composites fine α-Fe particles of several tens to hundreds nanometers were uniformly dispersed, though the surface of some particles may be oxidized by exposure to air. For the 1000°C product, magnetization assigned for iron was 154emu g-1, and the coercive force, Hc, 420Oe.

Reactivity with Tris(hydroxymethyl)aminomethane confounds immunodetection of acrolein-adducted proteins.

The toxic alpha,beta-unsaturated aldehyde acrolein readily attacks proteins, generating adducts at cysteine, histidine, and lysine residues. In this study, rabbit antiserum was raised against acrolein-modified keyhole limpet hemocyanin in the expectation that it would allow immunodetection of adducted proteins in biological samples. Using slot-blot and enzyme-linked immunosorbent assays, the antiserum detected acrolein-modified protein with high sensitivity and specificity. Adduct immunodetection was strongly inhibited by acrolein-modified polylysine but not polyhistidine. Efforts to develop a Western blotting method for detecting adducted proteins in cell lysates were hampered by irreproducible outcomes, evidently due to adduct instability during SDS-PAGE. Indeed, adducts generated via brief exposure of a model protein to acrolein displayed pH- and concentration-dependent instability to tris(hydroxymethyl)aminomethane (Tris), a nucleophilic buffer used in protein electrophoresis. The effect was most striking when Tris solutions were buffered to pH 8.0 and higher. In contrast, adducts formed during extended exposure to acrolein (> or =60 min) were completely stable to Tris. The time dependence of susceptibility raised the possibility that Tris interfered with specific steps in lysine modification, which involves stepwise Michael addition of two molecules of acrolein to the same residue, followed by condensation and dehydration to form a heterocyclic adduct, N(epsilon)-(3-formyl-3,4-dehydropiperidino)lysine. We hypothesize that carbonyl-retaining Michael adducts may react with Tris by forming imines with the primary amine of the buffer. Consistent with this idea, triethanolamine, a tertiary amine buffer unable to form imines, had no effect on acrolein-adducted protein. These effects of Tris may explain difficulties in the detection of acrolein-adducted proteins during conventional Western blotting procedures.

Solution Viscosity of a Moderately Stiff Polymer: Cellulose Tris(phenyl carbamate)

Zero-shear viscosities η0 of tetrahydrofuran solutions of cellulose tris(phenyl carbamate) (CTC), a moderately stiff polymer of persistence length q = 10.5 nm, were measured as a function of the polymer concentration c and molecular weight M. The molecular weight dependence of η0 at high concentration is definitely stronger than that of flexible polymers, reflecting the chain stiffness of CTC. The η0 data for higher molecular weight samples are favorably compared with the fuzzy-cylinder model theory, but it is necessary to consider up to the terms in c2 in the intermolecular hydrodynamic interaction (HI) when the M of CTC is low. When compared among polymers of the same contour length but different stiffness, the intermolecular HI becomes more important with decreasing q.

Isotropic−Cholesteric Phase Equilibrium in Solutions of Cellulose Tris(phenyl carbamate)

The isotropic−cholesteric phase boundary concentrations and interfacial tension were measured for tetrahydrofuran (THF) solutions of fractionated cellulose tris(phenyl carbamate) (CTC) samples. The phase boundary concentrations are compared with the scaled particle theory for the hard wormlike spherocylinder model as favorably as those for other stiffer polymer systems, though the theory does not consider effects of the intramolecular excluded-volume and intermolecular multiple contacts, both of which are appreciable for high molecular weight CTC samples. This may be due to cancellation of the two effects in the isotropic−cholesteric phase equilibrium. The interfacial tension γ between the coexisting isotropic and cholesteric phases for the CTC−THF system slightly decreases with molecular weight, and the asymptotic value is higher than those of other stiffer polymer systems. The dependence of the asymptotic γ on the persistence length is consistent with Cui et al.'s theory based on the second virial approximation, but its magnitude is much larger than the prediction of the theory, indicating that higher virial terms in thermodynamic quantities play a significant role in γ.

An experimental investigation of large amplitude reversible square wave voltammetry

Large amplitude square wave voltammetric experiments have been undertaken with model electrochemical system comprising aqueous solutions of tris(2,2′-bipyridine)osmium(II/III) and tris(2,2′-bipyridine)iron(II/III) redox couples, both of which exhibit reversible behaviour. Analysis of the current responses in the frequency domain were performed by means of Fourier transformation. Excellent agreement was obtained between the experimental voltammograms and those predicted by theory, both for single component solutions and for mixtures.

Characterization of microrough bioactive glass surface: surface reactions and osteoblast responses in vitro.

The current study characterized the in vitro surface reactions of microroughened bioactive glasses and compared osteoblast cell responses between smooth and microrough surfaces. Three different bioactive glass compositions were used and surface microroughening was obtained using a novel chemical etching method. Porous bioactive glass specimens made of sintered microspheres were immersed in simulated body fluid (SBF) or Tris solutions for 1, 6, 24, 48, or 72 h, and the formation of reaction layers was studied by means of a scanning electron microscope/energy dispersive X-ray analysis (SEM/EDXA). Cell culture studies were performed on bioactive glass disks to examine the influence of surface microroughness on the attachment and proliferation of human osteoblast-like cells (MG-63). Cell attachment was evaluated by means of microscopic counting of in situ stained cells. Cell proliferation was analyzed with a nonradioactive cell proliferation assay combined with in situ staining and laser confocal microscopy. The microroughening of the bioactive glass surface increased the rate of the silica gel layer formation during the first hours of the immersion. The formation of calcium phosphate layer was equal between control and microroughened glass surfaces. In cell cultures on bioactive glass, the microrough surface enhanced the attachment of osteoblast-like cells but did not have an effect on the proliferation rate or morphology of the cells as compared with smooth glass surface. In conclusion, microroughening significantly accelerated the early formation of surface reactions on three bioactive glasses and had a positive effect on initial cell attachment.

Cross interaction of β-amyloid peptide and prion protein fragments

This article presents kinetic studies of cross interaction ofβ-amyloid peptide and prion protein fragments. Synthesesof three peptides (β25–35, β22–35 and PrP 109–126) were performed. Those peptides were used for aggregation studies in PBS and TRIS buffers using HPLC with DAD detector. Comparison of aggregation of peptides alone and incombination with other fragments was investigated. In all cases aggregation was faster in PBS than in TRIS solution. Obtained results suggest that β-amyloid peptide and prion protein may interact to form macromolecular complexes with different ability for aggregation.

Decalcification of Bone for Histochemistry and Immunohistochemistry Procedures

Histochemistry is often performed on frozen or acrylicembedded calcified bone sections (although preparation of bone sections using these techniques can be difficult) yet imrnunohistochemistry is Inore often performed on decalcified bone sections. Unfortunately, decalcification protocols used routinely for bone histology may not be well suited for histochemical or irnmunohistochelnica1 staining of bone, and some protocols may have prolonged decalcification times, especially for bone from large marnmals, such as the horse. We have evaluated a fixation and decalcification protocol, using Zamboni's fixative and decalcificatioll with 20% ethylenediaminetetracetate-5% sucrose-0.1 M tris solution at +4°C, and found that this solution provides rapid decalcification of bone, preserves tissue morphology, and is suitable for both histochemistry and immunohistochemistry protocols. Continuous agitation of the solution with the bone specimens suspended on threads resulted in the most rapid decalcification. (The J Histotechnol 25:33, 2002)Submitted: July 30, 2001; Accepted with revisions: December 17, 2001

Decalcification of Bone for Histochemistry and Immunohistochemistry Procedures

Histochemistry is often performed on frozen or acrylicembedded calcified bone sections (although preparation of bone sections using these techniques can be difficult) yet imrnunohistochemistry is Inore often performed on decalcified bone sections. Unfortunately, decalcification protocols used routinely for bone histology may not be well suited for histochemical or irnmunohistochelnica1 staining of bone, and some protocols may have prolonged decalcification times, especially for bone from large marnmals, such as the horse. We have evaluated a fixation and decalcification protocol, using Zamboni's fixative and decalcificatioll with 20% ethylenediaminetetracetate-5% sucrose-0.1 M tris solution at +4°C, and found that this solution provides rapid decalcification of bone, preserves tissue morphology, and is suitable for both histochemistry and immunohistochemistry protocols. Continuous agitation of the solution with the bone specimens suspended on threads resulted in the most rapid decalcification. (The J Histotechnol 25:33, 2002)Submitted: July 30, 2001; Accepted with revisions: December 17, 2001

The spermatozoon of the African catfish: fine structure, motility, viability and its behaviour in seminal vesicle secretion

The spermatozoon of the African catfish Clarias gariepinus is a simple organized aquasperm although it reveals very unique characteristics: the cytoplasmic channel is lacking, the mitochondria form a complex structure and the arrangement of the centriolar complex is species specific. Semen has high initial motility rates (c. 70–90%) and swimming velocities (c. 120–140 μm s−1), the main swimming type is linear. Motility duration in water is 30 s and is prolonged only to 40 s in NaCl solutions or more complex bu ered motility activating saline solutions. A pH between 7.0 and 9.0 has no e ect on the sperm motility parameters. Motility is completely and reversibly suppressed in electrolyte and non‐electrolyte solutions with an osmolality of 200 mosmol kg−1. During immotile storage the sperm viability is influenced by the osmolality and the potassium levels of the storage medium, by the temperature and by the dilution. At optimal conditions (bu ered sperm motility inhibiting saline solution: 150 mmol l−1 NaCl, 2.5 mmol l−1 KCl, 1 mmol l−1 CaCl2, 1 mmol l−1 MgSO4, 20 mmol l−1 Tris solution, pH 8.5; dilution rate 1: 5; storage temperature, 4°C) sperm viability persists for >7 days. High viscosity of the pure seminal vesicle secretion completely inhibits the sperm motility. When the seminal vesicle secretion is diluted in water the viscosity decreases and the motility suppressing e ect is neutralized. When semen is mixed with seminal vesicle secretion the sperm viability decreases to zero within 10 min.

Hydrophilic and lipophilic iron chelators with the same complexing abilities.

A new series of iron chelators with the same coordination sphere as the water-soluble ligand O-trensox, but featuring a variable hydrophilic-lipophilic balance, have been obtained by grafting oxyethylene chains of variable length on a C-pivot tripodal scaffold. The X-ray structure of a ferric complex exhibiting tris(8-hydroxyquinolinate) coordination and solution thermodynamic properties (pK(a) of the ligands, stability constants of the ferric complexes) have been determined. The complexing ability (pFe(III) values) of the ligands are similar to that of O-trensox. Partition coefficients between water and octanol or chloroform have been measured and transport across a membrane has been mimicked ("shuttle process"). The results of biological assays (iron chelation with free ligands or iron nutrition with ferric complexes) could not be correlated with the partition coefficients. These results call into question the role of distribution coefficients (of the ligands and/or complexes) in the biological activities of iron chelators.