G. A. Vikhoreva

Solid state production of cellulose-chitosan blends and their modification with the diglycidyl ether of oligo(ethylene oxide)

Abstract Blends of the naturally occurring polysaccharides, cellulose and chitosan, obtained in the solid phase by the combined action of high pressure and shear deformation using various equipment, were studied. It was shown by IR-spectroscopy that the system of hydrogen bonds formed between hydroxyl and amino groups of the polysaccharides undergoes a qualitative change. This provides evidence that the blending of polysaccharides occurs at the molecular level. A mechanism of cellulose–chitosan blend formation in the presence of a diepoxide as a crosslinking agent was also studied. It was established that the crosslinking agent reacts predominantly at the amino groups of chitosan, with the formation of a three-dimensional network, cellulose macromolecules being located within and partially bound with this network by the crosslinks. It is shown that the formation of the aforementioned structures results in the insolubility of cellulose–chitosan compositions in acidic and alkaline aqueous media.

Thermal Modification and Study of the Structure of Chitosan Films

Using IR spectroscopy, elemental analysis, and potentiometric titration, it was confirmed that amidation and cross linking of the polymer take place in heat treatment of chitosan films in the S-form. It is shown that these processes also take place in hardening of films from formic acid solutions of chitosan by vaporization of the solvent at high temperature.

Preparation of biodegradable porous films for use as wound coverings

We studied the preparation of polymeric films formed from solutions of poly-3-hydroxybutyrate and poly-ε-caprolactone in chloroform and methylene chloride. A morphological study of film chips (electron microscopy) showed that solvent evaporation results in the formation of a heterogeneous structure with interpenetrating pores (1–20 μm). We proposed a new method for introducing the proteolytic enzyme and the aminopolysaccharide chitosan into the composition of polyester films. Composite films possessed necrolytic activity and were characterized by increased hydrophilicity. Properties of enzyme-containing films from a mixture of polymers (proteolytic activity, porous structure, and increased hydrophilicity) account for their use in the preparation of biodegradable wound coverings.

Reasons for unstable viscous properties of chitosan solutions in acetic acid

A decrease in the molecular mass of chitosan as a result of polymer degradation during storage of its acetic acid solutions has been simulated by means of mixing of chitosan fractions with different molecular masses. It has been shown that a decline in the polymer molecular mass is responsible for a reduction in the dynamic viscosity of chitosan solutions in acetic acid during their storage.

Antimicrobial Activity of Core-Sheath Surgical Sutures Modified with Poly-3-hydroxybutyrate

To impart antimicrobial activity to surgical sutures, weaved polyester fibers are coated with poly-3-hydroxybutyrate (PHB), containing the antimicrobial agent furazolidone (FZ). The prolonged FZ effect (7–14 days) is achieved by two-step application of a sheath, constituting 10% of the suture weight and containing 2–6% FZ. The sheath structure and antimicrobial activity of sutures can be modified by the introduction of other biocompatible and biodegradable polymers.

Modification of Chitosan Films with Glutaraldehyde to Regulate Their Solubility and Swelling

The possibility of fabricating enzyme-containing chitosan films with controllable swelling in aqueous media was demonstrated. The composition of spinning solutions that ensure a high (1000-2000%) degree of swelling of the films while preserving their integrity and strength was determined.

Synthesis and properties of water-soluble derivatives of chitin. A review

Concepts were formulated concerning the correlation of the structure and properties of an important class of biopolymers—aminopolysaccharides in aquatic organisms. Improved methods of obtaining water-soluble derivatives of chitin were developed, and their structure, physicochemical, and functional properties were characterized, including in the form of drugs, SF-PEC, and films.

Processing of chitosan biopolymer into granules, films, and fibers

Research of the last 10 years that was aimed at developing the theoretical bases for processing chitosan into granules, films, and fibers were reviewed. These items are interesting as sorbents, wound dressings, and separation membranes. Technically acceptable methods for preparing spherical granulated and fibrous, including nanofibrous, sorbents from chitosan and its composites with polyvinyl alcohol and potassium and copper hexacyanoferrate that exhibited high sorption capacity for heavy metals and radionuclides and were interesting for use in systems for reprocessing low-level liquid radioactive wastes and for performing ecological monitoring were developed.

Preparation and investigation of solutions of chitosan derivatives with long-chain hydrophilic substituents

The preparation of aqueous solutions of chitosan oligo(ethylene oxide) sulfonate and special features of their viscosity and foam-stabilizing properties are described. It is shown that the complete dissolution of the chitosan derivative takes place at a degree of substitution of at least 0.75. An increase in the degree of substitution to 1 leads to a decrease in the viscosity of solutions; however, the viscosity of solutions of chitosan oligo(ethylene oxide) sulfonate in all cases greatly exceeds that of solutions of chitosan acetate of the same concentration. Unlike chitosan acetate solutions, the solutions of chitosan oligo(ethylene oxide) sulfonate have a higher stability and more pronounced foam-stabilizing properties.

Study of cellulose-chitosan composites. Solid-phase modification, rheology, films

A method is proposed for processing of experimental data which would allow adequately describing the rheological behavior of systems whose disperse phase contains swelling particles of anisometric shape. Polysaccharide films with a high degree of swelling were obtained from dispersions of powdered cellulose in chitosan solutions. The high sorption capacity of the films, good adhesion to skin, lack of toxicity, and possibility of immobilizing drugs in them allow considering these films as promising materials for healing wounds and burns.