Chitosan ionic interactions

Sonvico F, et al. Formation of self-organized nanoparticles by lecithin/chitosan ionic interaction. Int J Pharm. 2006 324(l) 67-73. 

Binding enzymes to solid supports can be achieved via covalent bonds, ionic interactions, or physical adsorption, although the last two options are prone to leaching. Enzymes are easily bound to several types of synthetic polymers, such as acrylic resins, as well as biopolymers, e.g., starch, cellulose [52], or chitosan [53,54]. Degussa s Eupergit resins, for example, are used as enzyme carriers in the production of semisynthetic antibiotics and chiral pharmaceuticals [55], Typically, these copolymers contain an acrylamide/methacrylate backbone, with epoxide side groups... 

Another approach to reach delayed release from chitosan matrices are ionic interactions with polyanions. The formation of a polyelectrolyte complex membrane prevents early drug release. Via this method microcapsules can be formed between chitosan and alignate or even nanoparticles can be derived upon the complexation of chitosan with the polyanion tripolyphosphate. 

Fig. 10. Schematic representation of ionic interactions between alginate and chitosan at different pH [(a) pH 5.4 (b) pH 2.0]...

Similarly, the encapsulation of various molecules (BSA and dextrans with various molecular weights) in calcium alginate beads coated with chitosan has been reported [178,179]. Their release has been compared and the influence of the conformation, the chemical composition and the molecular weight of the encapsulated materials has been analyzed [178]. The ionic interactions between alginate and chitosan at different pH values are depicted in Fig. 10. 

Wu Y, et al. Chitosan nanoparticle formation by ionic interaction between PEG-Chitosan and tripolyphosphate. Int J Pharm 2005 295 235-245. 

A novel organic (chitosan) and inorganic (tetraethyl orthosilicate) composite membrane has been prepared, which is pH sensitive and drug permeable [258]. The latter possibly involved in ionic interactions. By plasma source ion implantation technique, the adhesion between linear low-density polyethylene and chitosan could be improved [259]. Such bilayer films showed 10 times lower oxygen permeability, a property of use in food packaging applications. These multilayer films were easily recyclable. 

However, for most applications, practical use of chitosan has been limited by its physicochemical properties, in particular its low solubility above pH 6.5 and the pH-dependence of the ionic interactions in the formulations. Hence, chitosan derivatives have been recently developed to widen and improve the potential biomedical applications of chitosan. 

Other ionic interactions can be exploited to create microgels or nanogels. Chitosan and carboxy-methyl chitosan have been associated to formulate nanoparticles containing tea polyphenols for sustained release of these antitumor compounds, Gelatin-dextran conjugates have been cross-linked with TPP for tea polyphenol delivery. ... 

Figure 1 Possible ionic interaction between algiitate and hydrolysed chitosan component ...

Cationic polymers are strongly adsorbed on the support by ionic interaction in distilled water. Although salt solutions are useful in preventing ionic adsorption, a rather high salt concentration is required. For example, salt concentrations below 0.4 M were not sufficient to prevent adsorption when some hydrophilic cationic polymers, glycol chitosan, DEAE-dextran and poly(trimethylaminoethyl methacrylate) iodide salt were separated on TSKgel... 

In the platelet adhesion assay, Af,0-snlfated chitosan with cationic NH3+ groups was shown to reduce platelet adhesion and activation by ionic interactions between the platelets membrane surface and the cationic groups on the modified chitosan manbrane. 

The positive charges on chitosan can also participate in ionic interactions, particularly with polyanions such as alginate, carrageen, and pectin. The complexes formed by electrostatic interaction between COO" or SO/" and NH/ (lUum 1998) have been proposed for the recovery of suspended solids from aqueous food processing streams (Mireles et al. 1992, Mireles-De Witt 1994, Torres et al. 1998, Savant and Torres 2000, Savant 2001) that can be used for animal feed (Wibowo et al. 2005a,b). 

In some cases (e.g., chitosan and gelatin capsules), ionic interaction can create ample binding during bath (exhaustion) treatment Chitosan is a biocompatible, biodegradable, and nontoxic polysaccharide which, as a result of its cationic character, is able to react with polyanions and give rise to polyelectrolyte complexes. For this reason, chitosan has been adopted for use in bath treatment processes. Because of these interesting properties, chitosan has become the subject of numerous scientific reports. 

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