Chemical Properties of Chitosan

Chitosan is totally non-toxic and its degradation products namely glucosamines are biocompatible. Although the gastrointestinal enzymes can partially degrade both chitin and chitosan, when both polymers are orally administered, they are not absorbed. Chitosan shows a LD50 of around 16 g/kg, very similar to the salt and glucose values in assays carried out on mice [1, 73]. Toxicity of chitosan is reported to depend on DAC, which decreases with increase in DAC. On the other hand, Mw of chitosan did not influence toxicity [73]. 

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The DD is the key property that affects the physical and chemical properties of chitosan, such as solubility, chemical reactivity and biodegradabdity and, consequently their applications. A quick test to differentiate between chitin and chitosan is based on solubdity and nitrogen content. Chitin is soluble in 5% lithium chloride/N,N-dimethylacetamide solvent [LiCI/DMAc] and insoluble in aqueous acetic add while the op>posite is true of chitosan. The nitrogen content in purified samples is less than 7% for chitin and more than 7% for chitosan (Dash et al, 2011 Rinaudo, 2006). 

The principle of functional group modification is to alter existing physical and chemical properties of chitosan in order to promote its capacity to deliver pDNA. Examples of vectors derived by functional group modification include thiolated chitosan (CSH) and A-acetylated chitosan. 

Kaimin sh, I.F., Physical-chemical properties of chitosan and possibilities of its practical application, 5-th All-Russia conference New perspectives in studying chitin and chitosan Proceedings, Moscow VNIIRO Publ., 1999, pp. 230-231 (in Russian). 

The effectiveness of zeolites in catalysis and separation can often be improved by the textural and chemical properties of the matrices in which they are imbedded. Chitosan gels issued from renewable resources are already used as supports for the preparation of heterogeneous catalysts in the form of colloids, flakes or gel beads [1, 2], In this study we present several methods for the incorporation of zeolites in chitosan matrices and characterize the synergic effect of the components on the properties of the composite. 

Because the biological properties of chitosan are dependent on its physico-chemical properties such as molecular weight (MW) and degree of deacetylation (DD), uniform physico-chemical properties are a prerequisite to specific industrial applications. As an alternative method, fermentation technology for chitosan preparation from fungal cell walls has received much attention as an eco-friendly pathway. Rane and... 

Chitosan has been the focus of reasearch as a pharmaceutical excipient due to its specific chemically and biologically favorable features [6-8]. As chitosan is soluble in acidic aqueous solutions, it can be processed under acidic conditions. By contrast, as the product made by chitosan is insoluble at neutral or basic pH, it behaves as a delivery system under such conditions. These chemical properties allow chitosan to control drug delivery. Further,... 

A. Structure, Physical, and Chemical Properties of Chitin and Chitosan... 

A. STRUCTURE, PHYSICAL, AND CHEMICAL PROPERTIES OF CHITIN AND CHITOSAN... 

Although chitosan-coated nanoparticles showed contradictory results in complement activation depending on the conformation of the chains at the nanoparticle surface [20], the level of complement activation induced by chitosan was also influenced by the physico-chemical properties of the polysaccharide, including its solubility, degree of deacetylation, and molecular weight [20, 96-98]. Using different... 

Suzuki Y, Okamoto Y, Morimoto M, et al. (2000). Influence of physico-chemical properties of chitin and chitosan on complement activation. Carbohyd. Polym. 42 307-310. 

This paper will focus on chitosan and chitosan derivatives developed for biomedical applications. In the first section, the remarkable properties of chitosan will be exposed. The main chemical modifications used to adapt this material for biomedical applications will be reviewed. Their applications in drag delivery systems and tissue engineering will then be discussed. 

In order to modify or enhance specific properties of chitosan, chemical derivatives have been synthesized by using the amines and hydroxyl groups in the molecular structure. Some examples include trimethyl chitosan, glycol chitosan, carboxymethyl chitosan, half-acetylated chitosan, and thiolated chitosan." ... 

The reactive hydroxy and amino groups of chitosan have been used for its derivatization or chemical modification. The amino group being nucleophilic in nature allows easy formation of imine bond with aldehyde or corresponding amide derivatives. However, in acidic solution, the cationic property of chitosan is revealed and the amino groups act like alkali, receive protons, and generate salts [87]. Some of the derivatives with their method of syntheses have been summarized in Table 15.2. 

In this chapter, we first discuss the chemical and physical properties of chitosan, including the synthesis, modification, molecular structure, characterization, and structure-property relationship. Second, we review the topics of biocompatibility, biodegradability, and antimicrobial activity of chitosan. These properties make chitosan a potential biomaterial for many biomedical applications. 

The two most important structural parameters that affect the properties of chitosan are the DDA and molecular weight These two factors together determine the physical, chemical, and biological properties of the biopolymer. As for any other polymer, these properties are an average of the contributions of all polymer chains in the sample. 

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