Diethylaminoethyl Groups Research Articles

Relationship between reduction of complement activation by polysaccharide surfaces bearing diethylaminoethyl groups and their degree of substitution

The relationships between substitution of hydroxyl (OH) by diethylaminoethyl (DEAE) groups on cellulose membranes and the resulting reduction of complement activation are not clear. As a model, Sephadex ® has been randomly substituted with DEAE groups. Modification of 10% of the glucose units, i.e. about 3% of the groups, had no noticeable effect on the complement activating capacity of the polymer surface, whereas 20% substitution dramatically reduced it. This result could be explained in part by the fact that Sephadex-specific antibodies are not adsorbed by this modified surface. Thus, they cannot enhance complement activation as they do on Sephadex or cellulose. Comparison of our results with those published on Hemophan ® led us to the conclusion that a similar effect could occur. However, the degree of substitution of the membrane surface is probably greater than that of the membrane core due to the preparation process. Comparison with Sephadex substituted with other groups, or with other polymers bearing a variable density of OH groups, led us to the conclusion that, as hypothesized by Chenoweth ( Artif Organs 1984; 8: 281–287), reduction of the availability of OH groups decreases complement activation, but the relationship is probably not linear. Moreover, replacement by other groups results in additional modulations due to (i) interactions between the groups and proteins responsible for formation or decay of the amplifying C3 convertase and/or (ii) decrease in recognition of the modified surface by antibodies which enhance complement activation on polysaccharides.

Interaction mechanisms between insulin and N-acetylneuraminic acid in affinity chromatography.

Silica beads are coated with dextran carrying a calculated amount of positively charged diethylaminoethyl (DEAE) groups in order to neutralize negatively charged silanol groups at the silica surface and in this way to minimize non-specific interactions between silica and proteins in solution. Dextran-coated silica supports are potentially excellent stationary phases for high-performance liquid chromatography of proteins. These supports combine the advantages of polysaccharide phases with the excellent mechanical characteristics of silica. These supports [silica-dextran-DEAE (SID)] are easily functionalized by grafting N-acetylneuramic acid (NANA), extracted from edible birds' nests, using conventional coupling methods. The performance of supports bearing NANA was studied by high-performance liquid affinity chromatography of insulin, the hypoglycaemic peptide hormone of the human organism. The study showed that these supports exhibit a reversible and specific affinity towards insulin and allow separations with high purification yields. The influence of different physico-chemical parameters (pH, temperature and insulin concentration) on insulin retention on the support was studied. This allowed the optimization of the conditions of adsorption and a better understanding of the interaction mechanisms between insulin and NANA as a biospecific ligand.

Development of cationically modified cellulose adsorbents for the removal of endotoxins.

The removal of endotoxins by extracorporeal adsorption processes seems the most promising therapeutic approach to Gram-negative sepsis and endotoxin shock. However, thus far adsorbents have failed to bind endotoxins efficiently or have shown adverse biocompatibility characteristics. To overcome these disadvantages, small particles of regenerated cellulose in the range of 1-8 microns in diameter were produced. Before use, the microspheres were cationically modified by substitution with polyethyleneimine (PEI) or diethylaminoethyl (DEAE) groups. A third kind of adsorbent was manufactured by (physically) coating the cellulose matrix with PEI. All three types of adsorbents exhibited a high adsorption capacity for endotoxins in human plasma, whereas activated charcoal and various anion exchange resins removed only small amounts of endotoxins under the same conditions. In addition, because the outer surface area is very large, adsorption takes place rapidly and diffusion becomes almost irrelevant. The adsorption process is primarily based on electrostatic interactions, which could be demonstrated by a significantly higher adsorption rate and binding capacity for lipid A-diphosphoryl, compared with lipid A-monophosphoryl. Use of these adsorbents in a newly developed plasma sorption system could be of great clinical interest because of the low production costs, the high adsorption efficiency, and the excellent biocompatibility data.

Body distribution of dextran derivatives with electric charges after intravenous administration

The body distribution of electrically charged dextran derivatives was investigated after intravenous administration of 125I-labeled dextrans. The effects of the charge density and molecular weight of dextran derivatives on their half-lives in the circulation and organ distribution were pharmacokinetically analyzed. The introduction of negative charges into the dextran molecule prolonged its half-life in the circulation. This trend became more marked with increasing molecular weight of the dextran, however, its half-life was reduced by derivatization with cationic diethylaminoethyl groups. The cationized dextran accumulated in the liver more significantly than the anionized and original dextrans. For example, approx. 10% substitution of dextran with the diethylaminoethyl group was sufficient to enhance the accumulation of dextran in the liver and spleen, but no effect of cationic derivatization was observed for the distribution in other tissues.

New Macrocyclic Ligands. III. Pendant 2-Pyridylmethyl and Diethylaminoethyl Arm Derivatives of Dibenzo-Substituted O2N2-Donor Rings. The X-Ray Structure of a Pendant 2-Pyridylmethyl Derivative

The syntheses and characterization of eight new 14 to 17-membered macrocycles incorporating O2N2-donor sets in the rings and pendant 2-pyridylmethyl or diethylaminoethyl groups, attached at one or both ring nitrogens , are reported. The X-ray structure of the mono(2-pyridylmethyl) derivative of the 15-membered macrocycle at c. 120 K is also described.

Preferential inclusion of nitrophenoxide ion over its conjugate acid in polycationic cyclodextrin: pK a decrease of nitrophenols by host-guest interaction with diethylaminoethyl-cyclodextrins

Diethylaminoethyl (DEAE) groups were introduced into α-cyclodextrin (α-CD) and β-CD. The products, DEAE-CDs with various numbers of substituents, trappedp-nitrophenoxide and 3,4-dinitrophenoxide preferentially over their respective conjugate acids. This caused a decreased pK a of the guest nitrophenol. Some signals of the proton-NMR of both guest nitrophenol and host DEAE-CD changed upon host-guest interaction. The relation between the number of DEAE groups and the extent of the pK a decrease, as well as association constants, is discussed.

NMR analyses of polysaccharide derivatives containing amine groups

Amylose, amylopectin, hydroxyethylcellulose, methylcellulose, and cellulose were reacted with diethylaminoethyl chloride HCl salt and 3-chloro-2-hydroxy-propyltrimethylammonium chloride under aqueous alkaline conditions in order to introduce tertiary amine and quaternary ammonium groups into polysaccharides. Degrees of substitution were obtained from 1H- or 13C-NMR spectra of hydrolyzates, and distributions of diethylaminoethyl groups in polysaccharides were measured by 13C-NMR. Since amylose, amylopectin, and hydroxyethylcellulose were soluble in the reaction media, these three polysaccharides had higher reactivity for etherifications than cellulose. Methyl-cellulose, which has hydrophobic methyl groups, had as much reactivity as cellulose. Primary hydroxyl groups, C-6, of polysaccharides had the highest reactivity for diethylaminoethylation.

Preparation of dietnylaminoetnyl hollow fibres for high-flow liquid chromatography

A novel anion-exchange column for fast-flow liquid chromatography was developed. The column was prepared by immobilizing diethylaminoethyl groups on to the inner walls of regenerated cellulose hollow fibres. A detailed investigation was conducted of the parameters affecting diethylaminoethyl immobilization such as the NaOH concentration, the reaction temperature, the diethylaminoethyl concentration and the reaction span. Based upon the findings, a protocol to optimize the preparation of the diethylaminoethyl hollow fibres was established. The diethylaminoethyl hollow fibres prepared adsorbed 186 ± 30 mg of albumin/g fibres.

Fluorometric study of the side-chain effect on protein adsorption character in cellulose-polymer composite ion exchangers

Abstract Cationic functional polymers carrying DMAE (dimethylaminoethyl), DEAE (diethyl-aminoethyl), DiPAE (diisopropylaminoethyl) and TBAE (tert-butylaminoethyl) groups were covalently linked to cellulose by a grafting process. Ion exchangers thus created exhibit high adsorption capacity for proteins and excellent mechanical strength. In this study, the protein adsorption character was examined at various pH values. A steep decline of capacity for BSA (bovine serum albumin) was observed as the pH increased above the pKa of the functional group. Although the pKas of the functional groups follow the order DMAE

Rapid analysis of serum lactate dehydrogenase isoenzymes by high-performance ion-exchange chromatography

The repetitive analysis of serum lactate dehydrogenase (LDH) isoenzymes has been performed on a weak anion exchanger (TSKgel DEAE-5PW), which was developed by introducing diethylaminoethyl groups into TSKgel G5000PW (10 microns particle diameter)--a hydrophilic polymer-based material of large pore size--for high-performance gel chromatography. By use of this anion exchanger, a high-pH (greater than 8.0) solvent could be used and the albumin peak was completely separate from the LDH isoenzyme peaks. After 10 successive analyses with an autosampler, the coefficient of variation of the LDH isoenzyme elution times was less than or equal to 0.90%, and the coefficient of variation for peak areas was less than or equal to 3.85%. After 40 successive analyses, resolution between isoenzymes was generally greater than 1.25. This column can be used for more than 300 intermittent injections of human serum.

Automatic analysis of serum lactate dehydrogenase isoenzymes by high-performance ion-exchange chromatography

The repetitive analysis of serum lactate dehydrogenase (LDH) isoenzymes has been performed on a weak anion exchanger (TSKgel DEAE-5PW), which was developed by introducing diethylaminoethyl groups into TSKgel G5000PW (10 μm particle diameter) — a hydrophilic polymer-based material of large pore size — for high-performance gel chromatography. By use of this anion exchanger, a high-pH (8.0) solvent could be used and the albumin peak was completely separate from the LDH isoenzyme peaks. After 10 successive analyses with an autosampler, the coefficient of variation of the LDH isoenzyme elution times was ⩽ 0.90%, and the coefficient of variation for peak areas was ⩽ 3.85%. After 40 successive analyses, resolution between isoenzymes was generally 1.25. This column can be used for more than 300 intermittent injections of human serum.

Preparative isolation of DNA and biologically active mRNA from diethylaminoethyl membrane

A simple method is described for the preparative isolation of both DNA and mRNA after electrophoretic separation in agarose gels. The method is based on the quantitative binding of the nucleic acid to a membrane containing charged diethylaminoethyl (DEAE) groups, followed by elution under high salt conditions. Fragments of bacteriophage λ cut with HindIII, ranging in size from 565 to 9536 bp were recovered at efficiencies ranging from 84% to 35%, respectively. Poly A + mRNAs from hen oviduct were recovered with an efficiency of 65–80%. Recovery of biological activity was about 70%.

Dynamic sorption and desorption of gold using Spheron DEAE as sorbent

The dynamic sorption and desorption of gold was studied using Spheron DEAE, a macroreticular hydroxyethyl methacrylate-ethylenedimethacrylate copolymer with chemically bonded diethylaminoethyl groups, as the sorbent. Factorial experiments were designed to optimize the composition of the mobile phase (H+ and Cl- ions); as a result, hydrochloric acid was used in a concentration of 0.01 mol l-1. Thiourea solution (0.4 mol l-1) in 0.25M hydrochloric acid served as the eluent: the gold sorbed was eluted completely in seven column volumes. A column of 1 cm3 volume retained gold quantitatively from 0.5 l of solution containing the metal in a concentration of 1 mg l-1 (5 μmol l-1); the recovery of gold by elution was 99% and the degree of concentration of gold with respect to the influent was a hundred. A method is worked out for a direct photometric determination of gold in the thiourea eluates, based on the decomposition of thiourea with hydrogen peroxide.

Polyelectrolyte complex of sodium dextran sulfate with dextran containing diethylaminoethyl groups

Polyelectrolyte complex of sodium dextran sulfate with dextran containing diethylaminoethyl groups

Synthesis of dimethyl esters of protoporphyrin ix and pemtoporphyrin

The dimethyl esters of protoporphyrin IX and pemtoporphyrin were synthesized by cyclization ofa,c-biladienes to the corresponding porphyrins, which containβ -diethylaminoethyl groups as potential vinyl substituents, and subsequent Hofmann degradation of them to vinylporphyrins in high yields.

Thermal Investigation of Diethylaminoethyl-Substituted Cotton Celluloses

The thermal behavior of diethylaminoethyl-substituted cotton celluloses was examined by thermogravimetric analysis, differential thermal analysis, and differential scanning calorimetry. Samples at levels up to 10% substituent content (prepared via an anhydrous sodium cellulosate method) were compared with other samples prepared by the conventional aqueous sodium hydroxide method. All thermal analyses were carried out in purified dry nitrogen or high vacuum at heating rates of 5-40°C/min. Considerable variation was observed when the samples in the base form were compared with those placed in the salt (hydrochloride) form. The effect of basic diethylaminoethyl groups on the cellulosic thermal degradation was shown in altered thermal patterns and Δ H of pyrolysis. In the hydrochloride form, lower Δ H of pyrolysis and decreased decomposition temperature were observed. These observations together with other minor thermal effects which were found to be associated with the decomposition, are compared with recent studies on the effect of inorganic bases on the pyrolysis of cotton cellulose.

Use of a sulphonic acid ion-exchange resin for the chromatography of insulin

We developed the synthesis of new supports for the purification of insulin and IgG by affinity chromatography. The preparation of such an affinity support is performed in two steps. First, silica beads are coated with dextran polymers carrying a calculated amount of positively charged diethylaminoethyl groups in order to mask negative charges at its surface. Second, ligand is immobilized using a coupling agent. This support combines the advantages of polysaccharide phases with the excellent mechanical characteristics of silica. The existence of N-acetylneuraminic acid (sialic acid) in insulin receptor and in the antigenic determinant of IgG suggests that such an acid may develop specific interactions usable in affinity chromatography. Therefore, N-acetylneuraminic acid was used as an active ligand. The immobilization of sialic acid can be carried out by using the conventional coupling agent: the carbonyldiimidazole. The performances of these supports grafted by sialic acid were studied by high-performance liquid affinity chromatography (HPAC). The optimization of the chromatographic conditions (support characteristics and mobile phase) enabled us to observe a behavior of the type “thiophilic” of the support, which does not contain sulfone group. This new affinity support allowed a one-step separation of the IgG from mouse ascitic fluids and also allowed the insulin purification from a pancreatic extract with a good purification yields.