Mussel biomimetic ZIF-8 nanoscale metal organic frameworks as stable and pH-responsive platforms for enhanced drug delivery

ZIF-8 NMOFs have been widely utilized in the field of nano-drug delivery system, due to the highly ordered porous structure, large specific surface area, and pH responsiveness. In this study, ZIF-8 NMOF was synthesized using 2-methylimidazole (H-MIM) as the ligand and zinc nitrate hexahydrate as the metal salt. Utilizing 5-fluorouracil (5-FU) as a drug model, mussel biomimetic chitosan (Cat-CS) modified NMOFs was constructed as a drug carrier through surface modification. The particle size, structure and morphology were characterized using DLS, SEM, XRD, FT-IR and TG, and the pH-responsive property of the NMOFs was investigated. The results showed that the average particle size of the NMOFs was 186.75 nm, and the drug loading capacity and encapsulation efficiency were 9.02 % and 64.79 %, respectively. In vitro controlled release studies showed that the sustained and controlled drug release can be achieved after surface modification, with maximum cumulative release rates of 63.80 %, 43.81 %, and 34.88 % at pH 1.4, 4.0 and 7.4, significantly increasing drug release under acidic conditions and demonstrating excellent pH responsiveness. In all, the prepared NMOFs exhibit excellent stability, pH-responsiveness and biocompatibility, further prolonging drug release time and improving bioavailability, which can be used as an ideal drug carrier to enhance the efficient drug delivery.