Magadiite-based delivery system with sustained release of gemcitabine and its cytotoxicity against HepG2 cells

A drug delivery system based on magadiite for gemcitabine (namely GEM-Mag) has been constructed by protonation, intercalation with tetrabutylammonium ions (TBA + ), and ion exchange. Various measurements were used to characterize the samples. XRD results showed that the basal spacing of Na-magadiite (15.17 Å) decreased to 11.40 Å after protonation. Following intercalation with TBA + , the basal spacing increased to 25.79 Å. After further ion exchange with the positively charged GEM, the basal spacing reduced to 18.21 Å. FT-IR and TG-DTG indicated that the GEM was incorporated into the magadiite. Based on CHN elemental analysis and EDS results, the chemical formula of GEM-Mag was estimated to be H 1.59 (C 9 H 12 F 2 N 3 O 4 ) 0.41 Si 14 O 29 ·2.33H 2 O. According to the chemical formula, the loading capacity of GEM-Mag for GEM was 10.74%. Drug release tests were carried out either in phosphate buffered solution (PBS, pH = 7.40) or in HCl solution (pH = 1.35). Results revealed that the GEM-Mag exhibited sustained-release of GEM. While the drug released for 96 h in the PBS, the cumulative release percentage of GEM from drug delivery system was only 53.46%; whereas in the HCl solution (pH = 1.35), the cumulative release percentage was 52.15% after 700 min. Cytotoxicity assay confirmed that the magadiite-based drug delivery system for GEM exhibited stronger inhibitory effects on HepG2 cells compared with that of the free GEM. In addition, the drug-loading process and mechanisms have been discussed in detail.