Chitin, deacetylation

LDPE 10803-020 (90,000 molecular weight, 53% crystallinity degree, and 0,917 g/sM density) and chitosan samples of Bioprogress Ltd. (Russia) obtained by alkalinedeacetylation of crab chitin (deacetylation degree 84%), and M = 115000 were used as components for producing biodegradable polymer films. 

The chitin is modified to impart the structure required by the functions of each particular tissue, via crystalHzation, deacetylation, cross-finking to other biopolymers (Fig. 1), and, in certain cases, quinone tanning. The resulting complex structures are capable of exceptional performances [15]. 

Isolated chitins are highly ordered copolymers of 2-acetamido-2-deoxy-/3-D-glucose and 2-amino-2-deoxy-j6-D-glucose. The occurrence of the latter is explained by the fact that in vivo chitin is covalently finked to proteins via the nitrogen atom of approximately one repeating unit out of ten, therefore upon isolation a degree of deacetylation close to 0.10 is found. Chito-biose, 0-(2-amino-2-deoxy-j6-D-glucopyranosyl)-(l 4)-2-amino-2-deoxy-... 

Recent progress of basic and application studies in chitin chemistry was reviewed by Kurita (2001) with emphasis on the controlled modification reactions for the preparation of chitin derivatives. The reactions discussed include hydrolysis of main chain, deacetylation, acylation, M-phthaloylation, tosylation, alkylation, Schiff base formation, reductive alkylation, 0-carboxymethylation, N-carboxyalkylation, silylation, and graft copolymerization. For conducting modification reactions in a facile and controlled manner, some soluble chitin derivatives are convenient. Among soluble precursors, N-phthaloyl chitosan is particularly useful and made possible a series of regioselective and quantitative substitutions that was otherwise difficult. One of the important achievements based on this organosoluble precursor is the synthesis of nonnatural branched polysaccharides that have sugar branches at a specific site of the linear chitin or chitosan backbone [89]. 

The rate of in vivo biodegradation of subcutaneous implanted films was very high for chitin compared with that for deacetylated chitin. No tissue reaction was foimd with highly deacetylated chitosans, although they contained abundant primary amino groups [240]. 

Partially deacetylated chitin, a cellulose-like biopolymer consisting predominantly of N-acetyl-D-glucosamine chains, in the form of films or crosslinked hydrogels has been used for the delivery of drugs (28,29). The suitability of chitin as a vehicle for the sustained release of drugs was examined using indomethacin and papaverine hydrochloride as model drugs (30). In vitro studies showed that over 80% of the indomethacin was released within 7 hr, whereas papaverine hydrochloride dissolved almost immediately. 

Chitosan is a naturally amine-functionalized polysaccharide which is easily obtained by deacetylation of chitin, a zero-cost residue of the seafood industry (Fig. 

Chitin and the deacetylated form, chitosan, are attractive linear amino polysaccharides found in the shell of crustaceans. These abundant biopolymers, composed mainly of poly(/T(l,4)-2-acetamido/2-amino-2-deoxy-D-glucopyranose)... 

As was made clear earlier, chitosan and its derivatives are of more value than chitin. Currently the chitin is deacetylated by a harsh alkali treatment. If they... 

Chitosan is produced from the deacetylation of chitin. Chitosan is employed in the food industry. It is a hemostatic from which blood anticoagulants and antithrombogenic have been formed. It is often sold as a body fat-reducing agent or to be taken along with food to encapsulate fat particles. 

Waste water treatment chitosan/ drugstore deacetylated diitin chitin of crustaceans, also fixmd in insects and fimgi... 

Tomihata, K. and Ikada, Y. (1997). In vitro and in vivo degradation of films of chitin and its deacetylated derivatives. Biomaterials 18, 567-575. 

Chitosan, the most abundant marine mucopolysaccharide, is derived from chitin by alkaline deacetylation, and possesses versatile biological properties such as biocompatibility, biodegradability, and a non-toxic nature. Due to these characteristics, considerable attention has been given to its industrial applications in the food, pharmaceutical, agricultural, and environmental industries. Currently, chitosan can be considered as a potential marine nutraceutical because its remarkable biological activities have been investigated and reported, in order to exploit its nutraceutical... 

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