Chitosan Microspheres: Modification of Polymeric Chem-Physical Properties of Spray-Dried Microspheres to Control the Release of Antibiotic Drug

Antibiotic drug releasing from chitosan and acylchitosan microspheres was studied. The acylchitosan microspheres were prepared by modifying the microencapsulation process from spray-drying to spray in-liquid coagulating process for the improvement of chem-physical properties of polymer in controlling the release of antibiotic drug. A higher yield of microspheres was recovered by this improved process. Crystallinity, swelling ability, and the morphology of various microspheres were investigated by X-ray, water adsorption, and scanning electron microscopy studies. Results show that by modifying the microencapsulation process from spray-drying to spray in-liquid coagulating process, the chemical properties of the microsphere were varied from a hydrophilic chitosan microsphere to a hydrophobic acylchitosan microsphere, while the physical structure of the microsphere was varied from a porous chitosan microsphere to a dense acylchitosan microsphere. For the reasons, drug release rate of acylchitosan microspheres prepared by the novel spray microencapsulation method were apparently depressed, and the long-acting release of antibiotic drug was possible to be achieved.