Release behavior of microspheres from cross-linked N-methylated chitosan encapsulated ofloxacin

摘要

A series of hollow microspheres encapsulated with ofloxacin have been successfully prepared,using cyclohexane droplets as a template and the N-methylated chitosan (NMC) cross-linked with glutaraldehyde as the shell.The structure and morphology were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM).The swelling and releasing behaviors of the microspheres having different weight-average molecular weights (M_w) and the degree of quaternization of NMC at pH 1.2 and 7.4 media were investigated.The results revealed that microspheres exhibited a very smooth surface,and electrostatic interaction existed between cross-linked NMC and ofloxacin.Ofloxacin encapsulated in the microspheres was rapidly released into phosphate buffer solution (pH 7.4),whereas it was only slowly released in 0.1 M HC1 (pH 1.2).The degree of swelling of microspheres at pH 7.4 was higher than that at pH 1.2.Moreover,ofloxacin was released more slowly from the microspheres having high M_w of NMC than that with low M_w.The release mechanism of the hollow microsphere was proposed to be a non-Fickan diffusion through the swollen microspheres,and to be controlled by the M_w and the cross-linking density of shell.