ZIF-8 as Potential Vector for Enhanced Target Delivery of Sulfathiazole for the Treatment of Bovine Ruminal Acidosis

The aim of this paper is enlarging the potential use of ZIF-8 MOF as drug delivery system (DDS) for antimicrobial molecules, in particular for sulfathiazole, to be employed for the treatment of Sub-Acute Ruminal Acidosis (SARA) in dairy cows. We therefore optimized (from milligrams to grams) the synthesis methodology for ZIF-8 MOF, moving from organic solvents to aqueous solution, deeply characterizing the prepared material with X-ray diffraction (XRD), surface area analyses (BET), electron microscopy (SEM), and thermogravimetric analyses (TGA). Once proved that the synthesis is also reproducible, we tested the stability of the material at physiological and acid pH, controlling material stability over time by checking their crystallinity with XRD. We then optimized sulfathiazole entrapment method to obtain the best material, checking the effective loading with UV-Vis spectroscopy. Afterwards, we checked the effective entrapment vs physical mixture by means of XRD, SEM and ATR-MIR spectroscopy. Finally we tested the pH-responsive drug release by dialyzing the sulfathiazole@ZIF-8 by UV spectroscopy on the dialysis solution, confirming the strong pH-dependence of release time of sulfathiazole.