Atomic Force Microscopy Study of the Surface of Films of Chitosan and Its Salts with Organic Acids

The results of the study of the morphology and surface topography of chitosan films of the salt (S-) and basic (B-) chemical form by atomic force microscopy are presented. The films were cast from polymer solutions in acetic, lactic, citric and succinic acid. NaOH and triethanolamine were used for the salt → chitosan base reaction. Surface tomograms were obtained; the main morphological characteristics and roughness parameters of the film samples were estimated.

Viscosity Properties of Chitosan Solutions in Glycolic Acid

Viscosity properties of chitosan solutions with molecular weights of 700 and 200 kDa in 1.5% glycolic acid were studied in a wide range of polymer concentration and ionic strength of the medium by means of capillary and rotational viscometry. The concentration dependences of the specific viscosity were plotted. The influence of the molecular mass of chitosan and the NaCl-controlled ionic strength of the medium on the hydrodynamic volume of macrochains and their polyelectrolyte properties was established. The size of a polyion with an almost completely compensated charge was estimated.

Synthesis and Physicochemical Properties of Grafted Copolymers of Chitosan and Acrylic Monomers

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. Glutaraldehyde was also used for cross-linking.

Influence of Ascorbic Acid Isoforms on the Hydrodynamic Behavior of Chitosan Ascorbate Macromolecules in Aqueous Solution

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.

Ionic Aggregation of Macromolecules as the Cause of the Kinetic (Non)Stability of Physicochemical Properties of Chitosan Solutions

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 viscosity drop effect is not affected by the use of untreated or sterile degassed distilled water to dissolve the polymer.

Polymeric Sorbents for the Collection of Oil and Oil Products from the Surface of Reservoirs: a 2000–2017 Review of the English-language Literature (Part 2)

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. The English 2000–2017 scientific and technical literature devoted to the design of sorbents based on polymeric materials for the collection (absorption) of spilled oil and oil products from the surface of reservoirs with the possibility of subsequent recovery of the useful product was searched and analyzed.

Synthesis and Functionalization of Magnetite Мagnetic Nanoparticles with Сhitosan

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.

In Vivo and in Vitro Studies of the Effect of Chitosan on the Bone Defect Repair Process

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.

Viscous Degradation of Acidic Chitosan Solutions and its Ionic Probe Study

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.

Influence of the Modifying Additive Nature on the Rheological Properties of the Concentrated Chitosan–Organic Acid–Water System

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.