Preparation and drug release property of tanshinone IIA loaded chitosan-montmorillonite microspheres.

In this study, a biocompatible chitosan/montmorillonite (CS/MMT) composite microsphere was developed as a carrier for loading and sustained-release of the hydrophobic drug of tanshinone IIA. Though the compatibility between hydrophobic drugs and hydrophilic matrix was fairly poor, tanshinone IIA was successfully loaded on the microsphere by the solvent exchange process during chitosan matrix dehydration. The microstructure of the resulting microspheres was characterized with several techniques, such as X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscope (SEM). The results of drug loading and in vitro release study of the tanshinone IIA loaded CS/MMT composite microspheres showed that the incorporation of MMT into CS matrix would enhance the drug encapsulation and retard drug migration. The sample with mass ratio of CS: MMT (10:2) exhibited highest encapsulation efficiency (48.18% ± 2.54%) and slowest continuous cumulative release of drug in phosphate buffer solution (pH 7.4). It was found that the tanshinone IIA release kinetics fit the Higuchi model and the release mechanism was non-Fickian diffusion. Cell viability studies by CCK-8 assay showed that the microspheres showed no obvious cytotoxicity at the dosages below 80 μg/ml, and the MMT content had no significant effect on cell viability. This work provided a successful method of incorporating hydrophobic drugs into hydrophilic matrices, and has been successfully applied to the preparation of effective and biocompatible drug delivery for tanshinone IIA.