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, physicochemicaI, and functional properties were characterized, including in the form of drugs, SF--PEC, and films.Cellulose polysaccharides and chitin are the two most widespread organic substances on Earth. The extent of the use and importance of cellulose are well known. Chitin is much less well known in this sense. One reason for this is that chitin is scattered in the oceans: crustacean shells are the main source. However, interest in chitin and its derivatives as objects for research and practical application has continuously increased in the past ten years. This is indicated by the increase in the number of publications and production volumes of these polysaccharides in industrially developed countries, primarily Japan and the USA. Russia is one of the countries that processes chitin and its best known derivative, chitosan, and the reserves potentially give Russia a leading position in the creation of these valuable polymers. We also note that depletion of the traditional sources --crab shells --can be compensated by the discovery of new sources such as krill shells, river crayfish, microscopic fungi, etc. [1,2].The product of deacetylation of chitin, chitosan, is the best known and investigated water-soluble derivative of chitin. The presence of ionogenic amino groups in chitosan determines many of its properties, including its consumer properties. Sulfated and carboxymethylated derivatives of chitin and chitosan are also of great interest. According to the published data, chitin and its derivatives can be used for different purposes, including for fabrication of fibres and films [3][4][5]. However, in consideration of the high cost and small production scales, using them for medical purposes, including as substances for pharmaceutical forms, suture and dressing materials, matrices for immobilization of biologically active substances, thrombusresistant coverings, selective membranes, etc., is most rational in this stage for assimilation of these polymers [6,7].The ash content and residual concentration of protein are usually the basic indexes for chitin and chitosan, while the degree of deacetylation (DA), i.e., the degree of conversion of chitin into chitosan, and the molecular weight (tool. wt.), which varies from 100,000 to 500,000 in commercial chitosans, are basic indexes for chitosan. The characteristics of the investigated crab and krill chitins and chitosans from different manufacturers are reported in Table 1. The high porosity of chitin in comparison to chitosan, high ordering of the supermolecular structure (65-80% degree of crystallinity) of chitosan and chitin from both sources, and the large size, defectiveness, and lower density of crystallites ofkrill chitosan were established as a result of a comparative study of the chemical...
