A Low Cytotoxic Cationic Metal–Organic Framework Carrier for Controllable Drug Release

A positively charged porous drug carrier MOF-74-Fe(III) (1, MOF = metal-organic framework), which could not be directly synthesized using ferric salts, was prepared through the oxidation of the neutral crystal MOF-74-Fe(II). This cationic host material exhibits very low cytotoxicity upon PC12 cells by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium (MTT) assay and high drug loading capacity of ibuprofen anions (∼15.9 wt %) through ion exchange and salt penetration procedures. Controlled by anion exchange, two mechanisms were involved in the drug release process with different drug delivery rates due to the presence of coordinated or free ibuprofen anions, making the administration of drug release more flexible.