chitosan

Chitosan (CS) with a viscosity-average molecular weight of 200 kDa and a deacetylation degree of 82 mol%, produced by Bioprogress Ltd. (RF) has been used in this work. Aqueous solutions of enantiomeric salt complexes of CS with L- and D-aspartic acid (AspA) have been obtained at an equimolar CS:AspA ratio, in terms of amino groups. Powders of CS·L-(D-) AspA salts have been isolated from the corresponding solutions by evaporation of water and stored in a desiccator at zero humidity.

The method presents obtaining hydrosoluble graft copolymer of complicated structure based on сhitosan, acrylamide (AM), sodium 2-acrylamido-2-methylpropane sulfonic (АМPS-Na) in order to obtain fl ocсulant which is resistant to salt of transition metals and heat temperature, and in order to use it as a reagent for oil production processes.

The influence of the nature of a modifying additive selected from the class of stabilizers and thickeners (high-molecular-weight chitosan, starch, xanthan gum, sorbitol, and pyridoxine hydrochloride) on the rheological properties of the concentrated chitosan–organic acid– water system (freshly prepared or stored at 4 and 20°C) was studied. It is shown that all the modifiers have a stabilizing and thickening effect, resulting in an increased viscosity of the multicomponent system and a lower rate of its fall in time.

A review of the literature on the phenomenon of aging (a significant drop in viscosity over time) of acidic chitosan solutions is given. A study was made on acetic acid (2%) solutions of chitosan of two viscosity-average molecular weights (200 and 46 kDa) by ion probing (addition of a KI solution). It has been indirectly confirmed that the motion of the probing ions in an electric field disturbs part (about a quarter) of the average macromolecule rather than the whole one.

The objective of our in vivo and in vitro studies was to examine the molecular and cellular mechanisms of the anti-inflammatory and wound-healing effects of chitosan barriers when used for guided tissue regeneration (GTR) in a rabbit model. An ELISA test of the rabbit blood serum conducted during the treatment of alveolar bone defects has confirmed the ability of chitosan to reduce inflammation fast by suppressing the TNF- cytokine production.

Superparamagnetic magnetite nanoparticles (MNP) have gained much attraction from the beginning of 21century because of its potential applications in biology, medicine, theranostics, physics, chemistry and chemical analysis due to unique multifunctional properties, including small size, superparamagnetic behavior, low toxicity, high adsorption properties used for magnetic solid-phase extraction (MSPE) in water purification and chemical analysis.

Oil spills after tanker and pipeline accidents pose a serious threat to the environment, lead to the loss of energy carriers and severely pollute seawater. Mechanical extraction by sorption mechanism is an effective means of oil spill liquidation from the surface of reservoirs.

Hydrodynamic, optical, colloid-flocculating, film-forming and structural morphological properties of diluted chitosan solutions (50–640 kDa) in acetate buffer (0.33 М СН3СООН + 0.2 М СН3СOONa), both initial ones and stored for ~1,850 days, were studied. It has been established that the decrease in the intrinsic viscosity of solutions over time is manifested for the reprecipitated and high-molecular-weight samples of chitosan to a greater degree.

The hydrodynamic behavior of chitosan macromolecules in aqueous solutions of ascorbic acid (AscA) diastereomers was studied by means of capillary viscometry. A comparison of these systems with chitosan solutions in such traditional solvent media as hydrochloric and acetic acids, Na-acetate buffer was made. Concentration dependencies of the specific viscosity were plotted, and the intrinsic viscosity and the Huggins constant were evaluated.

The search and analysis of English-language 2004–2019 scientific literature devoted to the graft polymerization of acrylic monomers (acrylic acid and acrylamide being examples) onto chitosan to obtain novel materials with valuable properties was made. It was revealed that radical copolymerization, with potassium or ammonium persulfate, cerium-ammonium nitrate being initiators was used for grafting. Microwave, UV radiation and gamma rays were also used. To obtain gel, a cross-linking agent (N,N’- methylenebisacrylamide) was introduced.