ИСТИНА

A number of studies are concentrated on the modification of polymers of chitin–chitosan series with metal nanoparticles. Chitin and chitosan, are known, to be bactericidal biopolymers, which makes reasonable the choice of these polymers as starting materials for the preparation of biodegradable film wound coatings and other materials with silver nanoparticles to enhance the effect. The aim of this study was to obtain stable macromolecular systems based on a water-soluble chitin derivative – carboxymethyl chitin (CMC) and silver nanoparticles (Ag-NP). Besides, we made an attempt to realize the mechanism of metal nanoparticles stabilization in CMC matrix in connection with shield composition of Ag-NP micelles. Nanosized silver particles used in the present work were obtained by biochemical synthesis or generated by radiation-chemical way in reversed micelles of an anionic surface-active agent - sodium bis(2-ethylhexyl) sulfosuccinate (AOT). Ag-NP were used in the form of reversed micellar solution (RMS) in isooctane or in the form of water dispersion of silver obtained from RMS. In the case of RMS (as a source of Ag-NP) we used ultrasonic treatment of heterophase system to transport Ag-NP from isooctane to water polymer solution. Stabilizing ability of the polymer matrix in the composite was investigated using FTIR. As a result of interaction between protons of CMC acetamide groups and the oxygen atom of AOT ester groups hydrogen bonds formation took place. Therefore, the increase in amide bond intensity in CMC-WDS system at 1608 cm-1, as compared to the peak at 1601 cm-1 and 1650 cm-1 of the initial polymeric matrix – CMC, was noted. In consequence of our preliminary studies, CMC was chosen as polymer matrix as long as it lacked functional groups competing with the stabilizing shield around Ag-NP micelles. Furthermore, metal nanoparticles in such polymer solutions are stabilized owing to steric protection of macromolecule fragments and hydrogen bonds AOT–CMC formation. To elevate the aggregative stability of Ag-NP in CMC matrix the number of plant antioxidants (AO) was investigated. The quantitative determination of Ag-NP and the evaluation of aggregative stability of nanoparticles in solutions with CMC were performed by measuring Ag-NP optical absorbance at 420 nm. Analysis by FTIR spectroscopy supported the hydrogen bonds formation between CMC and AO functional groups. Such interaction of AO with macromolecule resulted in improved stabilization of Ag-NP in CMC matrix. Thus, the anionic polyelectrolyte CMC can be successfully used as a matrix for producing composites with metal nanoparticles. In such a system, the polymer serve not only as a film-forming material but also as a stabilizer of metal nanoparticles and a modifier changing the affinity of the surface of hydrophobic nanoparticles for water molecules.