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 s tudied. The acylchitosan microspheres were prepared by modifying the microe ncapsulation process from spray-drying to spray in-liquid coagulating proce ss for the improvement of chem-physical properties of polymer in controllin g the release of antibiotic drug. A higher yield of microspheres was recove red by this improved process. Crystallinity, swelling ability, and the morp hology 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 coagula ting 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 thf novel spray microencapsulation method were apparently depressed, and the long-acting re lease of antibiotic drug was possible to be achieved. (C) 19991999 John Wil ey & Sons, Inc.