Materials Based on Chitin and Chitosan

In this chapter, the main characteristics of chitin and chitosan and the more convenient techniques used for their characterization will be presented together with their main physical properties. Furthermore, the materials obtained with these polysaccharides will be described. It is important to recall that chitin is a natural polymer that is also biocompatible and biodegradable, an important advantage for biomedical and pharmaceutical applications. Good film forming properties is valuable for packaging or other applications in the domain of materials. 

Bio-Based Plastics Materials and Appiications, First Edition. Edited by Stephan Kabasci. 2014 John Wiley Sons, Ltd. Published 2014 by John Wiley Sons, Ltd. 

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Commercially Available Wound Dressing Materials Based on Chitin and Chitosan. 19... 

Chitosan is called the last biomass of the twentieth century, and is a material that waits further development as an extraordinary biomaterial in the twenty-first century. Chitin and chitosan, derived from shellfish waste, continue to be underutilized resources. We believe that to further their development as a resource, that there are needs for products of intermediate value easy to produce and which capitalize upon the unique features of chitin and chitosan. Fibers and films based on chitin or chitosan have considerable promise for medical textile applications. The commercialization of chitosan-based hemostatic bandages, such as Hemcon , represents a significant accomplishment in gaining the acceptance of chitosan as a biomaterial. 

Hyaluronic acid is a linear polysaccharide formed from disaccharide units containing N-acetyl-D-glucosamine and glucuronic acid. Since it is present in almost all biological fluids and tissues, hyaluronic acid-based materials are very useful in biomedical applications. After cellulose, chitin is the second most abundant natural polysaccharide resource on earth. Chitin and its de-acetylated derivative chitosan are natural polymers composed of N-acetylglucosamine and glucosamine. Both chitin and chitosan have excellent properties such as biodegradability, biocompatibility, non-toxicity, hemostatic activity and antimicrobial activity. Chitin and its derivatives are widely used in various fields of medicine. 

Besides the naturally occurring cationic PS chitin and chitosan, a huge variety of semi-synthetic products is available, which are based on anchoring cationic groups onto the polysaccharide backbone. Examples include cationic starch and cationic cellulose derivatives, which are widely used for industrial purposes (cationic starch in paper ) and also in medical applications (cationic cellulose as additives, e.g. JR-400 and Quatrisoft LM-200 in hygienic products). However, applications in regenerative medicine are rather poorly developed for these materials and therefore a discussion is excluded at this point. 

This chapter gives a general introduction to the book and describes briefly the context for which the editors established its contents and explains why certain topics were excluded from it. It covers the main raw materials based on vegetable resources, namely (i) wood and its main components cellulose, lignin, hemicelluloses, tannins, rosins and terpenes, as well as species-speciflc constituents, like natural rubber and suberin and (ii) annual plants as sources of starch, vegetable oils, hemicelluloses, mono and disaccharides and algae. Then, the main animal biomass constituents are briefly described, with particular emphasis on chitin, chitosan, proteins and cellulose whiskers from molluscs. Finally, bacterial polymers such as poly(hydroxyalkanoates) and bacterial cellulose are evoked. For each relevant renewable source, this survey alerts the reader to the corresponding chapter in the book. 

In order to improve the properties of these unique polysaccharides and to develop new advanced materials, much attention has been paid to their chemical modification. These polymers have two reactive groups suitable for this purpose, namely, primary (C6) and secondary (C3) hydroxyl groups in the case of chitin whereas chitosan has additionally the amino (C2) group on each deacetylated unit. All these functions are susceptible to a variety of classical reactions which can be applied here in a controlled fashion to obtain a vast array of novel materials based on the two polysaccharides which can also be modified by either crosslinking or graft copolymerization. This topic has been extensively studied and thoroughly documented [5-7]. 

A prominent FDA-approved chitin dressing is rapid deployment hemo-stat (RDH) (Marine Polymer Technologies) which costs 300 per dressing. One study shows that polymeric hber material based on P-NAG is more effective than alpha-chitin or chitosan, since these have a heterogeneous structure and are complexed with minerals and proteins. Moreover, the j3 structure (parallel orientation) of the hbers was found to be more effective than the a structure (antiparallel orientation). In another study, the hemostatic and antibacterial properties of chitosan dressings have been shown to be improved by the addition of polyphosphate polymers and silver nanoparticles respectively. One limiting factor is that all forms of chitin or chitosan bandages are not equally effective and the effectiveness varies from batch to batch. ... 

Currently, commercial chitin and chitosan are extracted from industrial shellfish processing wastes (shrimp, crab, lobster). The seasonal character of those raw materials and the variability of the composition of the organisms make the process of chitin extraction rather expensive with low reprodudbillty. Moreover, they are subjected to environmental variations that impact on the products supply and quality [14,40,116]. Chitin is extracted from crustacean shells by the use of strong adds and/or bases that can cause deacetylation and depolymerization of chitin [119]. Alternative methods include the use of enzymes or proteolytic microorganisms (e.g.. Pseudomonas malto-philia, Bacillus subtilis. Streptococcus faecium, Aspergillus oryzae) that hydrolyze shellfish proteins and leave the associated chitin intact [119]. 

J. Kumirska, M.X. Weinhold, M. Czerwicka, Z. Kaczynski, A. Bychowska, K. Brzozowski, J. Thoming, P. Stepnowski, Influence of the chemical structure and physicochemical properties of chitin- and chitosan-based materials on their biomedical activity in A.N. Laskovski, ed.. Biomedical Engineering Trends in Materials Science-, InTech Rijeka, Croatia, pp. 25-64,2011. F. Gandia-Herrero, J. Cabanes, J. Escribano, F. Garda-Carmona,M. JimenezAtienzar, Encapsulation of the most potent antioxidant betalains in edible matrixes as powders of different colors, /. Agr. Food Chem., 61,4294-4302, 2013.. 

Radiation-induced main-chain degradation renders polysaccharides soluble, or at least increases their solubility, and therefore technical interests have focused on the radiation-induced main-chain degradation of certain biopolymers, such as cellulose, chitin and chitosan [96,104-107]. In being the main component of plants, cellulose is a widespread biopolymer. In technical processes, high-energy radiation treatment is applied to increase the solubility and to alleviate the hydrolysis of the constituent cellulose of plant-based raw materials. The G-values of the main radiolysis products, as reported by Ershov,... 

This review summarizes the industrial applications of natural polysaccharides such as Chitin and Chitosan based materials in wastewater treatment. In addition, this review also opens up various factors affecting the adsorption and desorption processes. We expect that this chapter will provide insights on the use of these natural polysaccharides for researchers woiking to discover new materials with new properties for the valuable applications. 

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