Preparation And Characterization Of Drug Loaded Polymeric Microcapsules

In this work, whey protein (WP) was chosen to coacervate with gelatin (GE) and gum acacia (AG) to form microcapsules, respectively. Oleyl acetate (i.e. cis-9-octadecenyl acetate, OA) and dedocyl acetate (DA), the component of insect sex pheromones, were used as the core materials. The structure of microcapsules and the release behavior were studied. With different shell and core materials, this work can be presented in 3 parts: (1) Encapsulation of OA by complex coacervation between WP and AG; (2) Encapsulation of DA by complex coacervation between WP and AG; (3) Encapsulation of OA by complex coacervation between GE and AG.(1) Encapsulation of OA by complex coacervation between WP and AG. OA, a component of insect sex pheromone, was synthesized using oleyl alcohol and acetic anhydride at oleyl alcohol/acetic anhydride molar ratio of 1/1.7 at 25 ?C for 3 h, using 0.2% of p-toluenesulfonic acid as catalyst relative to the total amount of oleyl alcohol and acetic anhydride. OA was characterized using IR and 1H NMR. Microcapsules containing OA were prepared through complex coacervation of WP and AG under the optimized experimental conditions. The loading and encapsulation rate of the core material were determined. It was found that the encapsulation rate increased with decrease in concentration of wall concentration. The release rate increased when decreasing the wall concentration. The fastest release rate was reached on concentration of 0.5%. Morphology of microcapsules containing OA was observed by scanning electron microscope (SEM). It revealed that the size of microcapsules was of 5~8μm, and the microcapsules possessed a core-shell structure with OA encapsulated in the inner of the microcapsules.(2) Encapsulation of DA by complex coacervation between WP and AG. DA, one of the components of insect sex pheromone, was synthesized through reaction of dodecanol with acetic acid at acetic acid/dodecanol molar ratio of 1.2 at 120°C using p-toluenesulfonic acid as catalyst and toluene as water-carrying agent. Microcapsules with DA as the core material and WP and AG as wall materials were prepared through complex coacervation. Through variations in core/wall ratios, concentrations of wall materials and cross linking agent in microcapsule preparations, encapsulation of DA and its release were studied. It was found that with the same polymer concentration, increasing core/shell ratio, the loading increased and so was the release rate. Beginning with 1.5% concentration, increasing wall concentration, the loading increased, and the release rate increased thereby. The release rate was suppressed when addition of glutaraldehyde as cross linking agent. Compared with the system of encapsulation OA with WP/AG, microcapsules manifested a two-step-release profile, i.e. a quicker constant start followed by a slower constant region. Besides, microcapsules formed by DA as core material manifested that there was a significantly enhanced in the release rate though the loading decreased.(3) Encapsulation of OA by complex coacervation between GE and AG. The optimized GE/AG system was used for the encapsulation of insect sex pheromone component OA. It was found that different from the encapsulation of OA with WP/AG, the high loading and the encapsulation rate could be reached only when glutaraldehyde was added as cross linking agent. The more cross linking agent were used, the higher loading and encapsulation rate were obtained. Compared with the system of WP/AG, the increase of wall concentrations made contributions to the both increase of loading and release rate. Microcapsules with core/shell structure were observed by SEM.