Synthesis of Chitosan-Based Nanomaterials
Basic concept of this method is to convert the material into microscopic droplets through emulsion and further stabilize the particles into nano size by cross-linking. Water-in-oil (w/o) emulsion is prepared under mechanical stirring by mixing chitosan aqueous solution into oil. A suitable surfactant is used to achieve the stable emulsion. The stable emulsion is cross-linked by using an appropriate cross-linking agent such as glutaraldehyde, formaldehyde, genipin, glyoxal, sulfuric acid, poloxamer, etc. For efficient cross-linking, overnight stirring of the reaction should be performed. Stirring rate is based on the volume of the reaction and desired physical properties of nanoformulation. A translucent solution obtained from overnight stirring is then filtered and washed repeatedly with n-hexane followed by alcohol to remove oil. The surfactant can be removed by precipitation with appropriate salts like CaCl2 followed by centrifugation. Resulted precipitates can then be lyophilized to get a fine dry nanomaterial (Akbuga and Durmaz 1994). Method is explained in Fig. 2.1.