Synthesis of hydrogels incorporating core–shell structured Fe3O4@ZIF-8 as bio-nanocomposite carriers for drug delivery

Due to its high porosity and excellent pH-sensitive breakdown, the zeolitic imidazolate framework-8 (ZIF-8) has been investigated as a drug delivery vehicle. To increase the magnetic property of ZIF-8 nanoparticles, Fe3O4 nanoparticles (Fe3O4 NPs) were encapsulated to form a core–shell structure (Fe3O4@ZIF-8). The core–shell particles were then incorporated into a hydrogel to increase biocompatibility. The Fe3O4@ZIF-8-incorporated hydrogel nanocomposite (Fe3O4@ZIF-8 hydrogel) was then studied for in vitro cytotoxicity for drug delivery applications. Transmission electron microscopy images confirmed the core–shell structure of the synthesized Fe3O4@ZIF-8 with a central Fe3O4 core and a shell of nano-sized ZIF-8. The specific surface area of the obtained Fe3O4@ZIF-8 was 821 m2 g–1 with a pore volume of 0.36 cm3 g–1. The effect of the prepared Fe3O4@ZIF-8 on cell viability (mouse fibroblast, L929 cell line) was investigated using an MTT (3-(4,5-dimethylthiazolyl-2-yl)-2,5-diphenyltetrazolium bromide) assay. The Fe3O4@ZIF-8 and pure ZIF-8 showed a 50% inhibitory concentration at 28.2 + 1.0 and 11.2 + 6.6 µg mL–1, respectively. A chitosan/pluronic F-127 hydrogel incorporating Fe3O4@ZIF-8 was successfully prepared and showed over 75% cell viability compared to the fresh culture medium. Overall results indicated the safety of using chitosan/pluronic F-127 vehicles containing Fe3O4@ZIF-8 as a carrier for drug delivery systems.