Chitosan structure

Fig. 9.5 Schematic representation of chitosan structure, a biopolymer composed of 2-amino-2-deoxy- P-D-glucose...

Fig. 3 SEM image of the chitosan structure obtained by low temperature water substitution followed by supercritical CO2 hydrogel drying. Reprinted from Journal of Supercritical Fluids 54 [65]. Copyright (2010) with permission from Elsevier...

Figure 15. 3D plot of loss spectra detected in neutralized chitosan (structure indicated where x=0.7 and y=0.3) in the temperature retnge from -120 to 150 C. The high temperature-low frequency range. The inset shows the Arrhenius-type dependence of relaxation times for the a process ( = 94 2 kJ mof ) (complete dielectric characterization in [149]). 

Domard, A., Domard, M., 2002. Chitosan Structure-properties relationship and biomedical application. In Dumitriu, S. (ed.) Polymeric Biomaterials. Marcel Dekker, New York, pp. 187-212. 

Figures 1 show the SEM photomicrographs of the silver containing chitosan fibers. It can be seen that although the silver containing chitosan fiber generally has a smooth surface structure, the AlphaSan RC5000 particles are visible and can be seen embedded into the chitosan structure. When the fiber is wet with 0.1% aqueous acetic acid solution, it can be seen under optical microscope that the silver containing AlphaSan RC5000 particles are fairly uniformly distributed inside the fiber structure, acting as the reservoir for releasing the antimicrobial silver ions.

Introducing small functional groups to the chitosan structure, such as alkyl or carboxymethyl groups (<9-/N-carboxyalkylation), can drastically increase the solubility of chitosan at neutral and alkaline pHs without affecting its cationic character. The conversion of chitosan to a variety of iV-alkylated derivatives can be achieved by treatment with aldehydes or ketones leading to formation of Schiff... 

STAGE II Ihe swelling reaches to its maximum and the degradation proceeds as the chitosan structure continues to decrease in MW. At this point, minute fragments are released into the surrounding medium resulting in a weight loss. 

It is widely recognized that specific interactions between polymers and mucins play an important role in mucosal adhesion at the molecular level. Khutoryanskiy et al. [126] have isolated and estimated the contribution of different physical interactions through manipulating chitosan structure via partial acetylation and adding NaCl, ethanol or urea. Although it was not possible to completely switch off selected interactions, Khutoryanskiy et al. have demonstrated that mucoadhesive interactions between chitosan and mucin are complex with contributions from electrostatic attraction. 

A/-acety I -o-gl ucosam i ne Figure 10.13 Chitin/chitosan structures. 

Jiang, T., et al., 2014. Micro- and nanofabrication of chitosan structures for regenerative engineering. Acta Biomaterialia 10 (4), 1632-1645. Available at http //linkinghub.elsevier. com/retrieve/pii/S 1742706113003425. 

FIGURE 10.6 SEM images of chitosan-MWCNT scaffolds of different chitosan/CNT ratios (a-d) macroporous structures at lower magnification (e-g) high magnification of scaffold walls presenting CNT distribution. Panels (a) and (e) show chitosan only panels (b) and (f), (c) and (g), and (d) and (h) depict chitosan structures with 2.5, 3.5, and 5.0 wt% CNT, respectively. (Reproduced with permission from Ref. [79]. Copyright 2008, American Chemical Society.)... 

In particular the natural polymer chitosan has emerged as a promising material for biological functionalization and improvement of specific biorecognition in MEMS and lab-on-a-chip device, since it is biocompatible and biodegradable, has unique chemical properties, and is easily deposited in thin-fihns (Koev et al., 2010 Yi et al., 2005 Wu et al., 2003). Chitosan has been reported for fabrication of nanowire and nanodot chitosan structures (Park et al., 2007), as well as films with controlled thickness (Zangmeister et al., 2006) and a variety of microscale... 

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