Synthesis and characterization of nanoscale zeolitic imidazolate frameworks with ciprofloxacin and their applications as antimicrobial agents

Abstract

The present study investigated antibiotic drug loading in metal–organic frameworks (MOFs). Porous zeolitic imidazolate frameworks (ZIFs) were synthesized under concentrated aqueous solution. A straightforward nano-precipitation method was used to prepare ciprofloxacin (CIP)-loaded ZIF-8 (CIP-ZIF-8). ZIF-8 and CIP-ZIF-8 were characterized by FT-IR spectroscopy, X-ray powder diffraction, scanning electron microscopy, thermogravimetric analysis, the BET nitrogen adsorption–desorption method, and UV-Vis spectroscopy. The thermal behavior of CIP-ZIF-8 was confirmed by thermal analyses. FT-IR spectroscopy illustrated the presence of functional groups of CIP and ZIF-8 frameworks in CIP-ZIF-8. ZIF-8 showed high loading capacity for the model antibiotic drug CIP with pH-sensitive release. The as-synthesized CIP-ZIF-8 possesses high drug loading efficiency (21%), and the release in pH 5.0 acetate buffer solutions (97%) was faster than in pH 7.4 phosphate buffers (83%). The antibacterial activities of ZIF-8 and CIP-ZIF-8 were tested against one Gram-positive and one Gram-negative species. The results showed that the synthesized materials had good growth inhibition against microorganisms.