Chitin biomedical applications

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. 

Jayakumar R, Prabaharan M, Nair SV et al (2010) Novel chitin and chitosan nanofibers in biomedical applications. Biotechnol Adv 28 142-150... 

Radhika M, Mary B, Sehgal PK (1999) Cellular proliferation on desamidated collagen matrices. Comp Biochem Physiol C Pharmacol Toxicol Endocrinol 124 131-139 Archana D, Dutta J, Dutta PK (2010) Synthesis, characterization and bioactivity with improved antibacterial effect of chitosan-pectin-titanium dioxide ternary film for biomedical applications. Asian Chitin J 6 26... 

Jayakumar R et al (2010) Novel chitin and chitosan nanofibers in biomedical applications. 

Jayakumar, R. Prabaharan, M. Nair, S.V. Tokura, S. Tamura, H. Selvamurugan, N. Novel carboxy-methyl derivatives of chitin and chitosan materials and their biomedical applications. Prog. Mat. Sci. 2010, 55 (7), 675-709. 

Jayakumar, R. Menon, D. Manzoor, K. Nair, S.V. Tamura, H. Biomedical applications of chitin and chitosan based nanomaterials—A short review. Carbohydr. Polym. 2010, 82 (2), 227-232. 

Chitin is one of the most abundant, naturally occurring polysaccharide. It is a (1 - 4) p-linked gly-can composed of 2-acetamido-2-deoxy-D-glucose. The deacetylated derivative of chitin is known as chitosan, which is the most extensively studied polymer for biomedical applications. Chitosan is a semicrystalline linear copolymer polysaccharide, consisting of (1 4) 3-linked D-glucosamine... 

Chitin is also used as excipient and drug carrier under film, gel or powder forms for applications involving mucoadhesivity [84], A recent review describes the use of chitin and chitosan as biomaterials in different biomedical applications [85], Different applications of chitin and that of few chitin derivatives are described in a recent book devoted to chitosan [86]. 

Nanofibrillar chitin hydrogels are biodegradable, biocompatible, and nontoxic, and thus show promise for biomedical applications. The protonation of amino groups on the surface of chitin allows its application in wound dressings due to the antimicrobial properties of cationic gels [130]. Polymeric fibers that mimic the structure and function of the extracellular matrix are also of interest in tissue engineering and cell culture. Chitin nanofibers can promote cell attachment and show potential as extracellular matrix mimics [29, 125]. 

This chapter focuses on the use of nanotechnology in the development of cellulose and chitin nanoctystals and their novel biomedical applications. It consists of four main sections. The first section is a brief introduction. The second section focuses on cellulose nanocrystals (CNCs) and their preparation procedure, physical properties, and surface modifications. Cationic modification of CNCs is also presented to produce positively charged CNCs. Various bioapplications of CNCs in bionanocomposites, drug delivery, and biosensors are discussed as well. The third section focuses on chitin nanoctystals (CHNCs). Except for a short introduction on chitin and its structure, the methods of isolation and characterization of chitin are discussed and the surface modifications and properties of CHNCs are summarized. The applications of CHNCs as reinforcing fillers in nanocomposites and several biomedical applications are discussed. The fourth section is a summary and perspective highlighting the future directions on the application of these natural nanoctystals in various key industries related to biomedicine. 

Chitosan is a very useful polymer for biomedical applications because of its biocompatibility, biodegradability and low toxicity. Chitin has also been described as biocompatible and biodegradable, and has found applications for specific purposes, such as sponges and bandages for the treatment of wounds and suture threads. However, it has generally received less attention than chitosan, because of its insolubility in water and low reactivity. 

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