V. P. Volodina

Enzymatic degradation of chitosan films under the action of nonspecific enzymes

The features of the enzymatic degradation process mediated by the nonspecific enzymes collagenase and Lyrase are discussed for chitosan films prepared from acetic acid solutions. It was shown that variations in the acid concentration in the initial solution have a substantial effect on both the structure of chitosan in the film formed and the degree of degradation of film samples.

Macromolecular effects upon enzymatic degradation of chitosan in solution

Macromolecular effects were revealed in the course of enzymatic degradation of chitosan in an acetic acid solution under the action of hyaluronidase, a nonspecific enzyme. It was shown that the concentration of chitosan in the initial solution determines its supramolecular organization and, hence, the degree of enzymatic degradation.

Composition of fullerene-containing styrene-diallyl isophthalate copolymers

The effect of fullerene C60 on the composition of macromolecules in the free-radical copolymerization of styrene with diallyl isophthalate is estimated. It is shown that the maximum amount of C60 is contained in the high-molecular-mass fraction of the products. Constants in the Kuhn-Mark-Houwink equation are determined for the fullerene-containing copolymer synthesized from an equimolar mixture of monomers.

Copolymerization of N,N-diallyl-N,N-dimethylammonium chloride and vinyl acetate

The free-radical copolymerization of N,N-diallyl-N,N-dimethylammonium chloride with vinyl acetate in DMSO, methanol, and a methanol-water (70: 30, mol %) mixture proceeds to yield statistical copolymers. The nature of solvents significantly affects the reactivity ratios of the comonomers. N,N-Diallyl-N,N-dimethylammonium chloride shows a higher reactivity than vinyl acetate. The kinetic features of the processes have been investigated, and the structure and properties of the copolymers have been studied.

Possible causes of “inconstancy” in the intrinsic viscosity of chitosan

It is found that there is substantial difference in the intrinsic viscosities of solutions of chitosan before and after its reprecipitation from acetic acid solutions. It is shown that this fact is not related to destructive processes, but is caused by the tendency toward a change in the supramolecular structure of chitosan during its dissolution in a thermodynamically good solvent.

Modification of hyaluronic acid and chitosan, aimed at developing hydrogels for ophthalmology

Modification of hyaluronic acid and chitosan with the aim of preparing hydrogels based on them was performed. The formation of a covalent bond between mitomycin C and hyaluronic acid modified with epichlorohydrin was demonstrated. Hydrogels based on hyaluronic acid dialdehyde and chitosan modified with succinic anhydride were prepared. The degree of modification and concentration of the polymers influence the gelation process. Prolonged release of mitomycin C from the hydrogel obtained was revealed.

Molecular characteristics and hydrodynamic behavior of polyelectrolyte-surfactant complexes in chloroform

Molecular characteristics of polyelectrolyte complexes of the ultrahigh-molecular-weight poly-(N,N-dimethyl-N-benzyl-N-methacryloyloxyethyl)ammonium chloride with oppositely charged surfactants in chloroform were studied by centrifugal sedimentation and viscometry. The effect of oil-soluble surfactants on the hydrodynamic properties of the complexes was examined.

Long-chain branching of “lanthanide” 1,4-cis-polybutadiene and conditions of its polymerization☆

The degree of branching of 1,4-cis-polybutadiene synthesized on a lanthanide-containing catalytic system has been investigated. The values of [η], the molecular mass and molecular-mass distribution of specimens synthesized under various conditions and having a wide polydispersity have been determined, together with the same properties of fractions of these specimens with a narrow molecular-mass distribution. It has been established that, depending on the conditions of synthesis on the lanthanide-containing catalytic system, specimens of polybutadiene may be obtained that are either linear or have a branched structure. A change in the proportions of Al and Nd has hardly any effect on the degree of branching whereas an increase in the temperature of polymerization leads to the appearance of long-chain branching.

Peculiarities of viscometric studies of enzymatic hydrolysis of chitosan

Enzymatic hydrolysis of chitosan (CTS) is studied by viscosity measurements, velocity sedimentation, and diffusion. It is found that the incubation of CTS in acetic acid solution is always accompanied by a decrease in the relative and intrinsic viscosity of CTS, but the chains are not destroyed in the process, as evidenced by the coincidence of the sedimentation constant and diffusion coefficient values with the values obtained for the initial CTS samples. The addition of enzymatic agents to the CTS solution results in a significant decrease in the sedimentation constant and an increase in the diffusion coefficient, indicating a decrease in molecular weight and the proceeding of enzymatic hydrolysis. Thus, the pattern of changes in the solution viscosity indexes, which can be affected by supramolecular structures of the polymer solution, has to be taken into account when using viscosity measurements.

Use of the Method of Determination of Concentrations of Reducing Sugars on Chitosan Enzymatic Hydrolysis

The possibility of using methods of viscosimetry and determination of concentration of reducing sugars on studying chitosan fermentative destruction was discussed.