POLYELECTROLYTE COMPLEX OF CHITOSAN AND CHONDROITIN SULFATE: FORMATION, PHYSICO-CHEMICAL PROPERTIES

Abstract

The formation conditions, stability and solubility of polyelectrolyte complex (PEC) of chondroitin sulphate (CS) and chitosan (CN) were studied. CS was isolated from cartilage of Atlantic salmon Salmo salar. The molecular weight determined by nephelometric method was 60 kDa. CN was prepared from the shell of crab Paralithodes camtschaticus, degree of deacetylation is 68.8%, molecular weight is 368 kDa. The conditions of PEC formation are established by mixing solutions of polysaccharides. The comparing the original polysaccharides and their interaction products was carried out on the basis of infrared (IR) spectra study. CS have revealed the presence of absorption near 1250 cm-1, corresponding to the asymmetric stretching vibrations of -SO2- group in organic sulfates. This absorption was absent in the spectrum of CN. In the IR spectra of the PEC this absorption of CS decreased in 2 times that correspond to molar ratio of CS and CN equals to 1:1. The absence of new bands in PEC spectrum compared with spectra of CS and CN was been explained the bonds formation due to electrostatic interactions. PEC formation conditions are studied. At the interaction of CN and CS the PEC suspension is formed, and then dense sediment of PEC drops out, whereas the molar ratio of these polysaccharides remains constant. At addition of solution of CS to the CN solution in the molar ratio 1:3; 1:6 the PEC dispersion is formed that preserves stability during 2-3 days. Possibility of practical application of the PEC formation reaction is considered. The titration of CS solution by CN solution with a known degree of deacetylation can be used to quantify the CS drug's purity. We investigated the possibility of quantitative extraction of CS directly from raw material using CN solution through formation and separation of insoluble PEC. To study the possibilities for further use of PEC its stability in aqueous solutions of electrolytes was considered. In alkaline there is partial dissolution of substances with the absorption close to CS absorption (1250 cm-1), in acid – to CS absorption. Thus, there is partial destruction of PEC in alkaline and acidic media with liberation of polysaccharides, each of which is dissolved at an appropriate pH: CS in alkaline medium, CN in acidic medium. Thus, the PEC formation, its properties and possibilities of practical application were studied in this work. For citation:Novikov V.Yu., Dolgopyatova N.V., Konovalova I.N., Kuchina Yu.A. Polyelectrolyte complex of chitosan and chondroi-tin sulfate: formation, physico-chemical properties. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N2. P. 60-66.