Preparation and characterization of chitosan/gelatin microcapsules containing triclosan

Chitosan/gelatin (C/G) microcapsules containing triclosan were prepared by a spray drying method. The core material, triclosan (TS) dissolved in octyl salicylate (OS), were emulsified in an aqueous solution containing variable ratios of chitosan/gelatin. The microcapsules were obtained by spray-drying the emulsions. On the scanning electron micrographs, the microcapsules were spherical and exhibited a core and shell morphology. The thermograms of the microcapsules showed no evidence for the melting of TS, suggesting that TS remained dissolved in the cores of the microcapsules and did not exist as a solid crystalline even after dry microcapsules were formed. According to the results of microelectrophoresis study, the point of zero charge of the microcapsules occurred around pH 9.0 and a higher content of chitosan in the microcapsule wall resulted in a higher positive charge of zeta potential. The degree of release of TS and OS from the C/G microcapsules in an aqueous solution of hydroxypropyl-β-cyclodextrin (HP-β-CD) was investigated. When chitosan is included in the wall of microcapsules, the degree of release was suppressed. This indicates that chitosan forms a more compact wall than gelatin. On the other hand, TS was released much more than OS. The preferred release of TS is probably due to the higher solubility of TS in the HP-β-CD solution.