Synthesis of UiO-66 loaded-caffeic acid and study of its antibacterial mechanism

The Zirconium-based metal-organic framework (UiO-66) has become important in the field of natural compounds delivery for its high drug loading capacity. Caffeic acid (CA) is a natural compound with unsatisfactory physicochemical stability. CA@UiO-66 improved the stability of CA and inhibited the growth of bacteria. UiO-66 was prepared by water-assisted method for the encapsulation of CA. CA@UiO-66 showed the highest CA loading rate of 56 % and a sustained-release ability of CA of 83 % until 100 h. It destroyed the surface morphology and ultrastructure of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The minimum bactericidal concentration (MBC) for E. coli and S. aureus were 1.0 mg/mL and 2.0 mg/mL, respectively. The 3-(4,5-dimethylthiazol-2-yl) 2,5-diphenyl-tetrazolium bromide (MTT) colorimetry showed that the CA@UiO-66 had low toxicity or no toxicity to human normal liver cells LO2 at the concentration of MBC. Therefore, CA@UiO-66 has a potential in the field of food microbial safety.