Application of Chitosan-Based Gels in Pharmaceuticals - Chitosan Based Hydrogels: Functions and Applications - page 313

Oil phase
(large volume)

Chitosan aqucous
solution

Emulsification
(w/o) emulsion

Cross-linking agent

Stir

Hardening of
droplets

Separation of
particles

Figure 7.1
Schematic representation of the preparation of chitosan particulate systems by the emulsion cross-linking
method.

particles are done by filtration/centrifugation followed by successive washings with hot
and cold water. The method is schematically represented in Figure 7.2 [1]. Varying the
compressed air pressure and spray-nozzle diameter controls the size of the particles and
then hardening particles by a cross-linking agent controls the drug release. In another
technique [5], a sodium sulfate solution is added dropwise to an aqueous acidic solution
of chitosan containing a surfactant under stirring and ultrasonication for 30 min.
Microspheres are purified by centrifugation and resuspended in demineralized water.

Blower

Chitosan solution

Alkali solution

Figure 7.2
Schematic representation of the preparation of chitosan particulate systems by the coacervation/precipitation
method.