Zeolitic Imidazolate Framework-8-Loaded Hydrogels as a Highly Biocompatible Carrier for Drug Delivery Applications

Zeolitic imidazolate frameworks-8 (ZIF-8), a type of metal-organic frameworks (MOFs), displays high porosity, large surface areas, and tunable functionality in nanocomposites, promising carrier for drug delivery applications. In this work, ZIF-8 nanomaterials were synthesized via precipitation under three different conditions and subsequently loaded onto chitosan/pluronic F-127 (CS/PL) hydrogels. The ZIF-8 materials prepared in NH4OH solution (ZIF-8-NH4OH) showed a regular cubic shape with a large particle size of approximately 963 nm due to the acceleration of crystal growth in a basic medium. Meanwhile, the ZIF-8 species prepared in H2O and MeOH (ZIF-8-H2O and ZIF-8-MeOH, respectively) displayed crystal sizes of approximately 152 and 240 nm, respectively. The overall toxicity of the ZIF-8 nanomaterials was determined with an XTT assay against the L929 mouse fibroblast cell line. The morphology of the cells was altered at a concentration of over 30 µg/mL due to cell membrane deformations. This result correlated with the lactate dehydrogenase (LDH) release study by detection of LDH release at a concentration of over 25 µg/mL (50% LDH release). To reduce the toxicity of the ZIF-8 materials, CS/PL hydrogels were appropriately prepared and used to encapsulate the ZIF-8 at 0.095% w/w. Cytotoxicity results of the ZIF-8-loaded CS/PL hydrogels indicated over 75% cell viability of the L929 cells. These results presented significant implications for future applications of the ZIF-8 particles in the delivery of drugs or other compounds.