Facile preparation of monodisperse hollow cross-linked chitosan microspheres

We have successfully prepared biocompatible and biodegradable hollow microspheres using carboxyl-functionalized polystyrene particles as core template and the chitosan cross-linked with glutaraldehyde as the shell. The monodisperse carboxyl-functionalized polystyrene particles were made by emulsifier-free emulsion polymerization. The structure, morphology, and constitution of the carboxyl-functionalized polystyrene particles were characterized by FTIR, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The structure, morphology, and formation process of the hollow crosslinked chitosan microspheres were characterized by FTIR, SEM, and TEM. The results revealed that the latex particles were removed by exposed to solvent and the microspheres exhibited the hollow structure. This work confirmed that the hollow microspheres were accomplished by fabricating on the basis of chemical cross-linking on the surface of the carboxyl-functionalized polystyrene particles and then removing off the cores of particles. Moreover, with the increase of carboxyl-functionalization degree at the surface of latexes and the increase of cross-linking period, the thicker and firmer monodisperse hollow microspheres were obtained. In addition, a watersoluble drug, salicylic acid, encapsulated in the microcapsules slowly released at pH 1.2. (c) 2007 Wiley Periodicals, Inc.