An iron–carboxylate-based metal–organic framework for Furosemide loading and release

An iron–carboxylate-based metal–organic framework, Fe-MIL100, has been synthesized using acid-free solvent at room temperature. Fe-MIL100 was prepared by combining Fe/H₃BTC/NaOH/H₂O (H₃BTC = trimesic acid) at a molar ratio of 1.5:1.0:x:880, where x is the varied NaOH concentration at 1.5, 3.0, and 5.0 M. The effect of NaOH molar concentration on the formation of Fe-MIL100 was studied. Characterizations of the Fe-MIL100 were carried out using powder X-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen (N₂) adsorption–desorption, and thermogravimetry analysis (TGA). The obtained Fe-MIL100, with x NaOH of 3.0 M, has an octahedral crystal shape (a = 73.41 Å), crystal size ranging from 100 to 400 nm, BET surface area of 1,446.4 m²/g, a pore volume of 0.829 cm³/g, and thermal degradation temperature of 358 °C. The potential of Fe-MIL100, a drug carrier device, was tested against Furosemide (a loop diuretic). As studied using the Langmuir adsorption isotherm model, 392.4 mg of Furosemide can be loaded per g of Fe-MIL100. The kinetic release of Furosemide was examined at 2 different biological pH of 5.8 and 7.4. The release profile of Furosemide was recorded within 24 h; it was found that the release profile follows the pseudo-first-order kinetics at pH 5.8 with a percent cumulative release of 41.56% and Korsmeyer–Peppas model at pH 7.4 with a percent cumulative release of 68.46%. The electrostatic repulsion drove the release of Furosemide from Fe-MIL100 due to the same negative charge of the compounds. Fe-MIL 100 at low concentration (< 30 μg/mL) shows good biocompatibility toward the 7F2 normal cell lines.