Chitin molecular structure

Chitosan Chitosan has a molecular structure similar to cellulose. This material is produced from chitin, which is widely found in the exoskeleton of shellfish and crustaceans. Chitin is the second most abundant natural biopolymer after cellulose. Chitosan is a good adsorbent for all heavy metals. It has been estimated that chitosan can be produced from shellfish and crustaceans at a market price of 15.43 /kg. 

Plant structural material is the polysaccharide cellulose, which is a linear p (1 —> 4) linked polymer. Some structural polysaccharides incorporate nitrogen into their molecular structure an example is chitin, the material which comprises the hard exoskeletons of insects and crustaceans. Chitin is a cellulose derivative wherein the OH at C-2 is replaced by an acetylated amino group (—NHCOCH3). Microbial polysaccharides, of which the capsular or extracellular (exopolysaccharides) are probably the most important class, show more diversity both in monomer units and the nature of their linkages. 

We used the crosslinked chitosan fiber (hereafter called ChF) in this experimental study. ChF was fabricated by Fuji Spinning Co., Japan. Fig.l shows the unit molecular structure of chitosan which was transformed from chitin by deacetylation. Chitin is a natural biopolymer which is contained in the shell of arthropods. Chitosan was crosslinked to make an adsorbent with acid, alkaline, and chemical proofs. The fabrication method of ChF was presented elsewhere.[S,6]. 

Figure 7.2 Molecular structure of chitin (R, R COCHa) and chitosan (R, R = H).

Figure 14.19 Molecular structure of Chitin. Adapted with permission from [97] Copyright 2014 Srpinger.

As already made known in the introductory part, chitin is also an abundant polysaccharide found in the exoskeleton of some arthropods and in the cell walls of many filamentous fungi. Cellulose and chitin differ in molecular structure only for a hydroxyl group at every ring in cellulose being replaced by an acetamido group in chitin (Stevens, 2002). As hard shells intended to support and protect the small bodies of crustaceans, these biocomposites must be subjected to less intense loads than larger trees, therefore the nanofibers become easier to extract. Add to that the possibility to cationize the... 

The molecular structure of chitin is shown in Figure 4.2. The crystallography of chitin has been investigated for a long time. Marguerite has reported in his reviews on chitin and chitosan at first glance the powder X-ray diagrams of chitins from shrimp shell (a-chitin) and anhydrous squid pen (p-chitin) appeared nearly the same. Further information on the crystalline structure of... 

Figure 19.7 Molecular correspondence of the inorganic-organic interface in the nacreous shell layer of Nautilus repertus. (a) Structural relationships between protein sheets, aragonite crystals and chitin fibres, (b) Possible complementarity of Ca binding. (From Mann et al., 1989. Reproduced with permission from John Wiley Sons., Inc.)...

This subject has been of continuing interest for several reasons. First, the present concepts of the chemical constitution of such important biopolymers as cellulose, amylose, and chitin can be confirmed by their adequate chemical synthesis. Second, synthetic polysaccharides of defined structure can be used to study the action pattern of enzymes, the induction and reaction of antibodies, and the effect of structure on biological activity in the interaction of proteins, nucleic acids, and lipides with polyhydroxylic macromolecules. Third, it is anticipated that synthetic polysaccharides of known structure and molecular size will provide ideal systems for the correlation of chemical and physical properties with chemical constitution and macromolecular conformation. Finally, synthetic polysaccharides and their derivatives should furnish a large variety of potentially useful materials whose properties can be widely varied these substances may find new applications in biology, medicine, and industry. 

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