Solutions In Organic Solvents Research Articles

Affinity Maturation of Tacrolimus Antibody for Improved Immunoassay Performance

Organic solvents used for extraction of tacrolimus from whole blood samples lower the apparent affinity of the antibody used in a diagnostic immunoassay, thereby affecting the detection limit. We used in vitro recombinant antibody engineering to screen and isolate clones from diverse libraries with mutagenic complementarity regions (CDRs) from tacrolimus 1-60-46 hybridoma cell line, with improved binding to tacrolimus in the presence of 10% methanol organic solvent solution. We isolated a number of clones with mutations in variable heavy (VH) CDR 2, variable light (VL) CDR 1, and VL CDR 3 with improved binding. Various combinatorial pairings constructed from these individual mutations contained >10-fold improvements in both the dissociation rate and overall equilibrium affinity constants. Selected clones produced as IgG have increased functional sensitivity, with a 3- to 6-fold reduction in the limit of detection relative to the parental tacrolimus 1-60-46 monoclonal antibody in the Architect Tacrolimus immunodiagnostic assay. The recent advent of recombinant in vitro antibody display technologies in general, and yeast surface display in particular, allows the flexibility to engineer new or augment specific analytical characteristics, such as affinity, specificity, or stability, into previously isolated and otherwise desirable antibodies to enhance assay performance. These in vitro selections can also be performed under conditions meant to mimic the assay in which the reagent will ultimately be used, to increase the likelihood of successful assay development.

Cuticular hydrocarbon analysis of an awake behaving fly using direct analysis in real-time time-of-flight mass spectrometry

In mammals and insects, pheromones strongly influence social behaviors such as aggression and mate recognition. In Drosophila melanogaster, pheromones in the form of cuticular hydrocarbons play prominent roles in courtship. GC/MS is the primary analytical tool currently used to study Drosophila cuticular hydrocarbons. Although GC/MS is highly reproducible and sensitive, it requires that the fly be placed in a lethal solution of organic solvent, thereby impeding further behavioral studies. We present a technique for the analysis of hydrocarbons and other surface molecules from live animals by using direct analysis in real-time (DART) MS. Cuticular hydrocarbons were sampled from the surface of a restrained, awake behaving fly by using several brief, carefully controlled depressions of the abdomen with a small steel probe. DART mass spectral analysis of the probe detected ions with mass-to-charge ratio (m/z) of the protonated molecule corresponding to many of the previously identified unsaturated hydrocarbons. Six additional cuticular hydrocarbons also were identified. Consistent with previous GC/MS studies, male and female differences in chemical composition were evident. Spatial differences in the expression profile also were observed on males. Sampling from an individual female first as a virgin and then 45 and 90 min after successful copulation showed that mass signals likely to correspond to cis-vaccenyl acetate, tricosene, and pentacosene increased in relative intensity after courtship. This method provides near-instantaneous analysis of an individual animal's chemical profile in parallel with behavioral studies and could be extended to other models of pheromone-mediated behavior.

Scanning electrochemical microscopy study of ion transfer process across water/2-nitrophenyloctylether interface supported by hydrophobic carbon ceramic electrode

A carbon ceramic electrode (CCE) modified with the redox probe—decamethylferrocene solution in hydrophobic organic solvent—2-nitrophenyloctyl ether and immersed into an aqueous solution was studied by scanning electrochemical microscopy (SECM). After the electrochemical oxidation of decamethylferrocene, its cations were detected near the electrode surface in the aqueous phase. This indicates that some fraction of the redox-active cations electrochemically produced in the organic phase is transferred across the liquid/liquid interface. They are reduced at the SECM tip and form a solid deposit. The amount of deposited decamethylferrocene was estimated by the anodic reaction at the tip. It is affected by the substrate–tip distance, deposition time, and electrolyte concentration. The SECM images of unmodified and modified CCEs are consistent with their heterogeneous structure.

Development of Enteric Coated Flurbiprofen Tablets using Opadry/acryl-eze System—A Technical Note

Tablet coating is perhaps one of the oldest pharmaceutical processes still in existence (1). It offers many benefits namely: improving the aesthetic qualities of the dosage form, masking unpleasant odour or taste, easing ingestion, improving product stability and modifying the release characteristics of the drug. It is widely used in enteric coating, controlled release system and osmotic pump systems (2). Enteric coated dosage forms are designed to resist the destructive action of the gastric fluid and to disintegrate in the higher pH environment of the intestinal fluid. Polymer for enteric coating can be applied to solid dosage forms (i.e. granules, pellets, or tablets) from aqueous solutions of alkali salts, or organic solvent solutions. The most commonly used pH-sensitive enteric coating polymers today include: cellulose acetate phthalate (CAP), cellulose acetate trimellitate (CAT), hydroxypropyl methyl cellulose phthalate (HPMCP) and methacrylic acid copolymers (3). In recent years, acrylic copolymers have evolved as the most preferred materials for designing enteric coating formulations in terms of performance and global acceptability (1). Aqueous enteric film coatings have been used widely in recent years. Many of these systems are pseudolatex dispersions of polymers such as CAP, latex dispersions of methacrylic acid copolymers and aqueous solutions of alkali salts (4).The advantages of an aqueous based coating system have been recognized. This is derived from the drawbacks of organic solvents including pollution, explosion hazards, and solvent toxicity. Especially there are risks for operators (5). Almost all nonsteroidal anti-inflammatory drugs irritate gastric mucosa and enhance ulceration by blocking protective action of the prostaglandins on gastric mucosa, causing ulcer formation not only in stomach but also in lower part of oesophagus and in duodenum too (6). The most important side effects of flurbiprofen include peptic ulceration, hemorrhage and perforation (7).The aim of current investigation was to develop an enteric coated flurbiprofen tablet formulation to minimize the gastric intolerance caused by flurbiprofen on long term use and to improve patient compliance by utilizing Acryl-Eze. Acryl-Eze is an optimized, one-step, pigmented, aqueous acrylic system for the application of an enteric film coating for oral solid dosage forms. Acryl-Eze combines the benefits and performance of a globally accepted enteric polymer (Eudragit® L100-55) with a fully formulated coating system, providing significant time savings in both development and production. Acryl-Eze has further been optimized for either tablet or multiparticulate applications (8). Eudragit® L100-55 is a copolymer of methacrylic acid and ethyl acrylate (1:1 ratio) which meets the USP definition for Methacrylic Acid Copolymer Type C. L100-55 is a re-dispersible powder produced by spray drying Eudragit® L30-D. Film coatings prepared from such dispersions are resistant to gastric juice but readily dissolve at a pH above 5.5 (9). EudragitL100-55 has been used as a coating polymer in several studies (10,11,12).

Estimation of the Gibbs energy of C60 fullerene solution in organic solvents based on the additive group method

The literature data on the Gibbs energy of C60 fullerene dissolution in organic solvents of different classes are analyzed. The contributions of the functional groups (-CH3,-CH2-, >CH-, >C<,-OH,-Ph,-Napht, etc.) of solvent molecules to the Gibbs energy of C60 fullerene solution were calculated based on the additive group model. The effects of different functional groups on the solution process are discussed.

Dispersions of alkyl-capped silicon nanocrystals in aqueous media: photoluminescence and ageing

Alkyl-capped silicon nanocrystals can be dispersed in aqueous media by shaking or stirring their solutions in organic solvents (DMSO, ether, THF) with excess water. THF is the most straightforward choice with which to prepare stable aqueous dispersions, because the nanocrystals are very soluble in THF and it is also miscible with water. As little as 0.01% v/v tetrahydrofuran is sufficient. DMSO and ether were the preferred choices for subsequent staining of live cells because THF shows some acute toxicity even when very dilute. The luminescence intensity of the aqueous dispersions is linear in particle concentration and independent of pH over the range 5-9. The sols retain their photoluminescence and are stable against flocculation for at least 6 months.

Gold recovery from loaded activated carbon using different solvents

The adsorption of gold complexes onto the activated carbon is the basis of modern techniques for gold recovery. The next step is the recovery of adsorbed gold from activated carbon with an efficient eluant. The objective of this study was to investigate an improved process for recovering gold from activated carbon. The process involves contact of gold laden activated carbon with a strong base at ambient temperatures followed by elution with an aqueous solution containing an organic solvent. Results showed that aqueous solutions of organic solvents, preferably aqueous solution of acetone or acetonitrile could be effectively used in the recovery of gold from loaded activated carbon which compared favorably with Zadra and AARL methods.

New chiral and restricted-access materials containing glycopeptides as selectors for the high-performance liquid chromatographic determination of chiral drugs in biological matrices

Two new chiral and restricted-access materials containing glycopeptide antibiotics as chiral selectors (chiro-Glyco-RAM) were designed, suitable for the direct HPLC injection of biological fluids containing chiral drugs without any sample pre-treatment or pre-columns coupling. The external surface of the porous silica support was covered with a bio-compatible hydrophilic polymeric network (polyvinyl alcohol, PVA) while the chiral phase based on either teicoplanin (TE) or teicoplanin aglycone (TAG) was exclusively confined to the internal region. The chiro-Glyco-RAM supports were synthesized by the following steps: (a) introduction of 3-aminopropyl groups on 100 Å pore size silica gel; (b) activation of the aminopropylated silica with 1,6-diisocyanatohexane; (c) functionalization of the external region of the porous silica with PVA; (d) covalent linking of TE/TAG to the internal surface. The average pore diameter of the chiro-Glyco-RAM supports, calculated by inverse size-exclusion chromatography (ISEC), was about 80 Å and able to exclude macromolecules heavier than about 20,000 Da (such as the most abundant serum proteins) from the pores. The recovery of bovine serum albumin (BSA) was almost quantitative. HPLC analyses of model chiral drugs were performed using hydro-organic mobile phases consisting of an organic solvent (acetonitrile or methanol) and aqueous solutions of ammonium acetate (0.020 M) or ammonium formate (0.0025–0.0050 M).

Effect of addition of organic solvents on properties of the chemically synthesized polyaniline in aqueous solutions

AbstractIn the process of polymerization of aniline in aqueous solution, different kinds or volumes of organic solvents were added. The effects of the organic solvents on the morphology, structure, conductivity and water-dispersity of the resulting polyaniline (PANI) were investigated with the aid of SEM, UV-Vis, FT-IR and Raman spectra and conductivity measurements. The results showed that the weak H-bond interactions between PANI and the solvents might play an important role in forming uniform nanofibers with relatively high conductivity and good waterdispersity. However, excessive addition of organic solvents led to the aggregation of the nanofibers and the corresponding PANI had a bad water-dispersity.

Soluble Functionalized Carbon Nanohorns

Carbon nanahorns (CNH) were functionalized following the methodology of 1,3-dipolar cycloaddition of azomethine ylides and found to form stable solutions in either organic solvents or water. The number of added functional units, in the form of pyrrolidine moieties, was calculated when a pyrene chromophore was utilized in the modification scheme. Moreover, complementary theoretical calculations revealed that reactivity enhancement is expected at locations near the conical-shaped tip of CNH, where the highest curvature and strain exist. Finally, additional organic transformation of already modified CNH was exploited by covalently linked ferrocene units.

Corrosion Suppression During Wet Processes in FEOL and BEOL for 45nm Node and Beyond

Galvanic corrosion of metal gates in front end of line (FEOL) is a serious problem during wet processes for technology devices of 45 nm node and below. We attempt galvanic corrosion to suppress with high selectivity for High-k/SiO2 using a water-less solution of organic solvent and HF. We succeeded in suppressing corrosion of metal gates using IPA + HF solvent for FEOL processes. In the back end of line (BEOL), corrosion suppression for Cu wiring with porous low-k is an important issue. In particular, an environmentally safe inhibitor instead of BTA is important. This paper reports the technology for the suppression of corrosion of metal gates and an environmentally safe inhibitor (Adenine) for Cu/low-k.

Synergetic effect of organic solvents and paraoxon on the immobilized acetylcholinesterase

The toxicity of organophosphorus pesticides is attributed to their ability to inhibit acetylcholinesterase (AChE), which catalyses the hydrolysis of the neurotransmitting agent acetylcholine (ACh). A simple, reproducible and stable AChE-based amperometric bioelectrode was used, for measuring the enzyme activity before and after the incubation with paraoxon dissolved in organic solvents. The inhibition percentage induced by a paraoxon in organic solvent solutions increases in the following sequence: acetonitrile < water < hexane, suggesting that the paraoxon repartition between the organic solvent and the essential water for enzyme activity plays an important role in establishing the analytical and kinetic parameters of the bioelectrode. Considering the AChE denaturation, induced only by the organic solvent, as a pseudo-inhibition process, the kinetic treatment of the bioelectrode response revealed that it follows a mixed competitive/non-competitive mechanism, while the inhibition due to a non-aqueous solution of paraoxon corresponds to a non-competitive/uncompetitive mechanism. In the last case, the synergetic effect of denaturation and inhibition of enzyme was dominated by the inhibitor presence.

Syntheses of siloxane-grafted aromatic polymers and the application to pervaporation membrane

The syntheses of siloxane-grafted poly(amide-imide) and polyamide were carried out by a macromonomer method, in order to develop a highly permeable and durable membrane material for pervaporation. A novel compound, 3,5-bis(4-aminophenoxy)benzyloxypropyl-terminated polydimethylsiloxane ( BAPB- PDMS), was synthesized as a macromonomer. BAPB- PDMSs with different PDMS segment lengths were prepared by hydrosilylation of 3,5-bis(4-nitrophenoxy)benzyl allyl ether with hydrosilyl-terminated PDMS using Pt catalyst, followed by hydrogenation reduction of the terminal dinitro groups. The polycondensations of BAPB- PDMSs with trimellitic anhydride chloride and terephthaloyl chloride yielded the desired siloxane-grafted poly(amide-imide) ( PAI- g - PDMS) and polyamide ( PA- g - PDMS) copolymers, respectively. The copolymer membranes were prepared by solvent-casting method, and the gas permeability and pervaporation property of these membranes were evaluated. As the solubility of the copolymers depended on the main chain structure, PA- g - PDMS membrane was insoluble in any solvents after it was dried in vacuo. The gas permeability coefficients of these copolymer membranes were increased as increase of PDMS segment length, and these values of PAI- g - PDMS were higher than those of PA- g - PDMS containing the same PDMS segment length. From the results of pervaporations of the dilute aqueous solutions of organic solvents, it was found that PA- g - PDMS exhibited the excellent permselectivity toward several organic solvents, such as alcohols, acetone, tetrahydrofuran, chloroform, dichloromethane and benzene with a high and stable permeation. Furthermore, it was confirmed that the removal of tetrahydrofuran from its dilute aqueous solution was efficiently achieved by the pervaporation using PA- g - PDMS membrane.

Large-Scale Synthesis, Size Control, and Anisotropic Growth of &lt;I&gt;&amp;gamma&lt;/I&gt;-Fe&lt;SUB&gt;2&lt;/SUB&gt;O&lt;SUB&gt;3&lt;/SUB&gt; Nanoparticles: Organosols and Hydrosols

Monodispersed, spherical gamma-Fe2O3 nanoparticles with controllable size in large-scale were prepared by thermolytic decomposition of FeCl3.6H2O in aliphatic amines. The nanoparticles gave very stable colloidal solution in organic solvents and can be easily converted to water-soluble by a very simple route. Their characterisation was based on TEM microscopy, XRD, Mössbauer, and magnetic measurements. Furthermore, a small amount of Pt can lead to the formation of anisotropic gamma-Fe2O3 nanostructures.

Single-walled carbon nanotubes with DNA recognition

Two methods for attaching DNA to oxidized single-walled carbon nanotubes either in organic solvent or aqueous solution are described. The sites of DNA attachment to the nanotubes have been verified by binding gold nanoparticles modified with DNA of complementary sequence to the DNA-modified nanotubes, and imaging with TEM. The gold nanoparticles appear on the tips of the nanotubes, and at isolated positions (defects) on the sidewalls. The methods provide versatility for the modification of nanotubes with DNA for their directed assembly, or for their composites with gold nanoparticles, into nanoscale devices.

Crystal structure of 3,5-bis(phtalimidomethyl)benzene-tert-butyldimethylsilyl ether, C30H30N2O5Si

Article Crystal structure of 3,5-bis(phtalimidomethyl)benzene-tert-butyldimethylsilyl ether, C30H30N2O5Si was published on June 1, 2007 in the journal Zeitschrift für Kristallographie - New Crystal Structures (volume 222, issue 2).

Environmental Friendly Surface Treatment of SBS Rubber with Acidified Chloramine T Aqueous Solutions

Abstract As environmental friendly alternative to the halogenation treatment with trichloro isocyanuric acid solutions in organic solvents (TCI/MEK), in this study a water-based surface treatment for rubber materials based in chloramine T aqueous solutions has been proposed. It was found that the effectiveness of chloramine T (CT) (N-chloro-sodium-p-toluenesulphenamide) as chlorinating agent for rubber depends on the pH of the chlorinating solution. The surface modifications and adhesion in one SBS rubber treated with aqueous solutions of CT has been studied. Acidification of CT aqueous solutions produced the formation of dichloramine T (DCT) and hypochlorous acid (HClO), species which reacted with C = C bonds of the butadiene units. A decrease in the pH of the CT aqueous solutions produced more extended surface modifications and improved adhesion properties in the joints produced with chlorinated SBS rubber and waterborne polyurethane adhesive. T-peel strength values obtained were slightly lower than those obtained for the SBS rubber surface treated with the organic solvent chlorinating system (TCI/MEK). The solvent effect leading to local swelling and therefore to deeper modifications in the rubber near surface properties was not present with water based solutions, and then, the modifications were much more superficial. On the other hand, acidification with hydrochloric acid produces deposition of NaCl crystals on the SBS rubber surface. Thus, acidification of the chloramines T solution with sulfuric acid was preferable.

Supramolecular Structures from Lysine Peptides and Carbon Dioxide.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Microinhomogeneity for Aqueous Mixtures of Water-miscible Organic Solvents

Mixing states for aqueous solutions of water-miscible organic solvents, acetonitrile and 1,4-dioxane, have been investigated at the molecular level by means of small-angle neutron scattering (SANS) and NMR relaxation. It has been shown that the organic solvent and water molecules are inhomogeneously mixed each other at the molecular level, although their mixtures are homogeneous at the macroscopic scale. Thus, both organic solvent clusters and water clusters coexist in the mixtures. The present investigation has also revealed that the microinhomogeneity of acetonitrile-water and 1,4-dioxane-water mixtures is gradually enhanced by cooling or adding salts toward phase separation. Based on the results, the effect of microinhomogeneity for solvent mixtures on chemical reactions was considered.

Wbudowanie chelatujacego układu iminowego w terpolimery metakrylanu glicydylu

Suspension terpolymer glycidyl methacrylate / styrene / diethylene glycol dimethacrylate, characterized with epoxy groups content about 1.4 mmol/g, low crosslinking degree and good swelling in a number of typical organic solvents, was subjected to two-stage chemical modification. The reactions with ethylene diamine and salicylaldehyde [equations (1) and (2)] were carried out in turn. The products obtained were characterized based on FT-IR spectra (Fig. 1 and 5) and nitrogen content (Table 1). Salicylimine resins obtained were applied to cobalt(II) ions sorption from the binary solutions of organic solvents (swelling/non-swelling ones), differing in compositions. The effects of the type and part of swelling solvent on the course of sorption were investigated (Fig. 3-4 and 6).