Distribution Of Amino Groups Research Articles

Insight into the distribution of amino groups along the chain of chemically deacetylated hyaluronan

Deacetylated hyaluronan (daHA) containing reactive free amino groups is an important intermediate for further modification. Comparing direct and indirect NMR and HPLC to characterize the degree of HA deacetylation (DD), direct NMR approach using area ratio of anomeric CH and CH–NH2 groups was the most precise one. To describe the substitution pattern, daHA was selectively cleaved by nitrous acid generated in situ or hyaluronan lyase from Streptococcus pneumoniae. The resulting oligomers were identified by LC-ESI-MS. The experimental distribution of these oligomers was compared with theoretically expected random oligomer distribution. Independently on the starting HA molecular weight and deacetylation conditions, the experimental data differed from the random distribution model and suggested that deacetylation of certain N-acetyl-d-glucosamine had reduced the probability of deacetylation at the neighbouring disaccharide. This phenomenon was explained by conformational changes of HA caused by intra- and intermolecular interactions between positively charged amino and negatively charged carboxylic groups.

Direct amination of diamond surfaces by electroless treatment in liquid ammonia solution

Diamond presents many interesting properties in terms of biocompatibility, chemical inertness and is attractive for applications notably in the biosensor field. The formation of amine functional groups at the diamond surface is of great interest for biomolecule's immobilization. In this work, we present for the first time, the “electroless” amination of diamond surfaces exposed to a liquid ammonia solution containing persulfate. Chemical surface modifications were followed by XPS analyses, while the distribution of amino-groups was studied by gold nanoparticles immobilization. This combined approach proved the growth of amino groups at the diamond surface during the electroless treatment.

Gold nanoparticles immobilization: Evidence of amination of diamond surfaces in liquid ammonia

Diamond presents many interesting properties in terms of biocompatibility, chemical inertness and is attractive for applications notably in the biosensor field. The formation of amine functional groups at diamond surface is of great interest for the incorporation of biomolecules. In the present work, we present an efficient direct amination method using anodic treatment in liquid ammonia on oxygen terminated diamond surface. Chemical surface modifications were followed by XPS analyses, while the distribution of amino-groups was indirectly studied by gold nanoparticles immobilization. The resulting surfaces were examined using FEG-SEM imaging. This combined approach has been powerful evidencing both the presence of notable amounts of amino groups after the electrochemical treatment in NH3liq and their homogeneous distribution at the diamond surface.

Amino functionalized mesostructured SBA-15 silica for CO2 capture: Exploring the relation between the adsorption capacity and the distribution of amino groups by TEM

The distribution of amino groups on amino-functionalized SBA-15 materials for CO2 adsorption was studied by transmission electron microscopy (TEM) in combination with a staining technique using RuO4 in order to analyze the influence of the aminated organic chains location on the CO2 adsorption properties. Mesostructured amino-functionalized SBA-15 materials were obtained by co-condensation, grafting and impregnation using aminopropyl, AP(N), ethylene-diaminepropyl, ED(NN), diethylene-triaminepropyl, DT(NNN) and polyethyleneimine, PEI, as functionalizing agents. CO2 adsorption isotherms of functionalized samples at 45°C showed that both the adsorption capacity (mgCO2/g ads) and the efficiency of amino groups (mol CO2/mol N) depend on the functionalization technique and the amount of organic compound used. While samples synthesized by co-condensation showed negligible CO2 uptake and efficiency, adsorbents prepared by grafting and impregnation presented significant CO2 adsorption capacities but a dissimilar efficiency. Key differences in the location of aminated chains explained the performance of CO2 capture for every adsorbent, being grafted samples the adsorbents where amino groups were better distributed, favouring CO2 diffusion trough the whole structure.

Structural and Biological Characterization of Aminated-Derivatized Oat β-Glucan

beta-Glucan extracted from oats was subjected to reductive amination, producing a cationic beta-glucan derivative of which physiological properties were characterized. The degree of substitution was obtained from elemental analysis, which was 0.48. In addition, the distribution of amino groups in the beta-glucan derivative was investigated by FT-IR analysis. In vitro bile acid binding capacity of the aminated beta-glucan was examined, showing significantly higher bile acid binding activity than native beta-glucan. Moreover, the beta-glucan derivative showed pronounced antimicrobial effects against Escherichia coli and Bacillus subtilis, and ACE (angiotensin-converting enzyme) inhibition activities which were dependent on its concentration. Furthermore, bronchoalveolar lavage (BAL) experiments demonstrated that the beta-glucan derivative stimulated the synthesis of nitric oxide. The improved functionalities of the derivative could be explained by its polycationic characteristics.

Histochemical Studies of Amino Groups in Frozen Sections

New histochemical methods for the demonstration of protein-bound amino groups are described. The reagent, 1, 2-naphthoquinone-4-sulfonic acid, was used to demonstrate the presence of primary amino groups in unfixed frozen sections. A reddish brown precipitate was formed at the sites of reactivity in tissue sections. The second method was based on the coupling of diazotized amine with β-naphthol to form an azo dye.The staining reaction of all tissues studied was completely blocked by pretreatment of the tissue sections with formaldehyde ; however, acetone or ethanol-fixed sections were stained moderately well.The distribution of amino groups in cardiac muscle, kidney and liver from normal rats and rabbits has been observed.