Chitosan microspheres and sponges: Preparation and characterization

In this study, chitosan microspheres and sponges were prepared and characte rized for diverse biomedical applications successfully. The chitosan micros pheres were obtained with a "suspension crosslinking technique" in the size range of 30-700 mu m. The stirring rate of the suspension medium and the c hitosan/acetic acid ratio, emulsifier, and crosslinker, that is, the glutar aldehyde concentration in the suspension medium, were evaluated as the effe ctive parameters on the size/size distributions of the microspheres. The mi crosphere size/size distributions were increased with the decreasing of all effective parameters except the chitosan/acetic acid ratio. In the second part of the study, chitosan sponges were prepared with a solvent-evaporatio n technique and sponges were cross-linked either during the formation or af ter the formation of sponges by using a cross-linker, that is, glutaraldehy de. When the sponges were crosslinked during the formation, fibrillar struc tures were obtained, while the leaflet structures were obtained in the case of crosslinking after the formation of sponges. In the last part of the st udy, the swelling behavior of both the chitosan microspheres and sponges we re evaluated using different amounts of the crosslinker. The swelling ratio was increased in both types of structures, that is microspheres and sponge s, by decreasing the amount of the crosslinker. (C) 2000 John Wiley & Sons, Inc.