Chitin, biodegradable polymers

McCormick, C.L., D.K. Lichatowich, and M.M. Fooladi, "Controlled Activity Pendant Herbicide Systems Utilizing Chitin and Other Biodegradable Polymers," Proceedings of the 5th International Symposium on Controlled Release of Bioactive Materials, pp. 3.6-3.17, Gaithersburg, MD (1978). 

In addition to synthetic biodegradable polymers discussed so far, naturally occurring biopolymers have also been used for fabricating implantable dmg delivery systems. Examples of natural biopolymers are proteins (e.g. albumin, casein, collagen, and gelatin) and polysaccharides (e.g. cellulose derivatives, chitin derivatives, dextran, hyaluronic acids, inulin, and starch). 

Chitosan Chitosan is a nontoxic, biodegradable polymer obtained by hydrolysis of chitin, a natural polysaccharide that is a chief component of the crustacean exoskeleton. Unmodified chitosan is soluble in acidic media and has significant muco-adhesive properties. 

There are many kinds of natural biodegradable polymers. They are classified into three types according to their chemical structures, i.e., polysaccharides, polypeptides/proteins and polynucleotides/nucleic acids. Among them, polysaccharides, such as cellulose, chitin/chitosan, hyaluronic acid and starch, and proteins, such as silk, wool, poly( y-glutamic acid), and poly(e-lysin), are well known and particularly important industrial polymeric materials. 

There are several kinds of natural biodegradable polymers in addition to bacterial PHAs, such as proteins, nucleic acids and polysaccharides. Among them, particulary important polymers such as industrial materials are polysaccharides, such as starch, cellulose, chitin and chitosan. The solid-state structure and properties of starch and amylose [127], cellulose [128] and chitin... 

The use of chitosan as a means of controlling the release of amino-acids has been also investigated by Rhone-Poulenc (ref. 5). Chitosan (deacetylated chitin) is extracted from shrimp and crab shells. It is known as a non-toxic, biodegradable polymer (Fig. 5). It is insoluble in water at neutral pH and has the capacity to dissolve at low pH values. Chitosan solutions are prepared by dissolving the polymer in dilute acetic acid. Stearic acid and oleic acid are the hydrophobic constituents in the chitosan-based coatings. 

Chitosan is obtained from the deacetylation of chitin, which is found in marine environments. Because it is insoluble in water, chitosan is dissolved in acidic solutions before being incorporated into biodegradable polymer films. It can also be plasticized with glycerol to obtain a kind of thermoplastic material like, for instance, plasticized starch (Epure, 2011]. 

Abstract Nature is gifted with several nanomaterials which could be obtained from different animal and plant sources. Cellulose, chitin and starch are abundant, natural, renewable and biodegradable polymers. By intelligent processing techniques they could be used as classical nano reinforcing fillers in polymers i.e., composites. They are often called whiskers. 

Chitosan. Chitosan (CH) is a natural biodegradable polymer. CH is a copolymer of glucosamine and N-aeetyl-u-glucosamine. It is derived by alkaline de-N-acetylation of chitin, whieh in turn is derived from... 

Other biodegradable polymers include Konjac, a water-soluble natural polysaccharide produced by FMC Chitin, another polysaccharide that is insoluble in water and Chitosan, which is soluble in water. Chitin is found in insects and in shellfish. Chitosan can be formed from chitin and is also found in fungal cell waUs. Chitin is used in many biomedical applications, including dialysis membranes, bacteriostatic agents, and wound dressings. Other applications include cosmetics, water treatmenfi adhesives, and fungi-cides. y... 

Biodegradable polymers can be classified into three categories according to their origin (i) synthetic polymers, particularly aUphatic polyesters, such as poly (L-lactide) (PLA) [1-3], poly(e-caprolactone) (PCL) [4—6], poly(p-dioxanone) (PPDO) [7-9], and poly(butylene succinate) (PBS) [10-12] (ii) polyesters produced by microorganisms, which mainly correspond to different poly(hydroxyalkanoate)s (e.g., poly(P-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate)) and (iii) polymers derived from natural resources (e.g., starch, cellulose, chitin, chitosan, lignin, and proteins). 

Chitosan is a water-insoluble, nontoxic, edible, biodegradable polymer (polysaccharide) that is obtained commercially from chitin by alkaline deacetylation [103]. Chitosan is the second most abundant biopolymer in nature after cellulose. Since chitosan is a polycationic polymer, its high sensitivity to moisture limits its applications. One way to overcome this drawback is to blend the material with humidity resistant polymers such has PLA. Suyatma et al. [104] combined hydrophilic chitosan with hydrophobic PLA (92% L-lactide and 8% mesolactide, Mw = 49,000 Da) by solution and film mixing, resulting in improved water barrier properties and decreased water sensitivity of the chitosan films. However, testing of mechanical and thermal properties revealed that chitosan and PLA blends are incompatible. 

Chitin and its derivatives are natural, nontoxic, biodegradable polymers with a broad range of commercial properties and applications. Although these biopolymers can be used in various industrial fields, this chapterfocuses on the use of chitin derivatives in the functional foods and dietary supplement industries. Many studies have reported the im-muno-modulatory effects in the form of antibacterial, anti-inflammatory, antioxidant, anticarcinogenic, or antiulcer activity [186-188] and found that chitosan derivatives are nonallergenic, so the body is not... 

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. 

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