Easily Coating Zeolitic Imidazolate Framework (ZIF-8) with Basic Magnesium Hypochlorite (BMH) Achieves an Efficient Antibacterial Strategy

This study synthesized zeolitic imidazolate framework (ZIF-8) using a solvothermal method and employed mechanical stirring to coat basic magnesium hypochlorite (BMH) onto the surface of ZIF-8, thus preparing antibacterial microspheres of BMH/ZIF-8. Escherichia coli ( E. coli ) was used as the model bacterium, the effect of BMH concentration on the antibacterial effect of BMH/ZIF-8 was explored, and the optimal BMH concentration was determined to be 100 µg/mL. The antibacterial rate was 73% for BMH, 20% for ZIF-8, and 100% for BMH/ZIF-8, as determined by the plate counting method. In addition, the synergistic effect factor (SEF) determination method calculated SEF > 0. This shows that BMH and ZIF-8 had a synergistic antibacterial effect. Important techniques such as Scanning Electron Microscope (SEM), Brunauer-Emmett-Teller (BET), and X-ray Diffraction (XRD) analysis were employed to investigate the synergistic antibacterial mechanism of BMH and ZIF-8. The mechanism is that porous ZIF-8 with ultra-large specific surface area cooperates with BMH to antibacterial. This synergistic effect allows BMH sheets to be adsorbed on the surface of ZIF-8, greatly increasing the contact area between the antibacterial agent BMH and bacteria. Additionally, BMH adsorbed on the surface of ZIF-8 can also serve as surface protection, thus delaying the breakage of Zn-N coordination bonds within ZIF-8. Consequently, as BMH on the surface of ZIF-8 is gradually consumed, the Zn-N coordination bonds undergo breakage, leading to slow release of internal Zn 2+ and 2-methylimidazole organic ligands. Zn 2+ possesses oxidizing properties, enabling it to bind with bacteria and disrupt their protein structures. Meanwhile, 2-Methylimidazole can undergo degradation, resulting in the generation of reactive oxygen species (ROS). The hydrophobic methyl group of 2-Methylimidazole is also able to compromise the integrity of bacterial membranes and impede the activity of key enzymes by means of chelating metal ions. Collectively, these mechanisms, in conjunction with ROS, establish a multifaceted antimicrobial network, thereby engendering a favorable antimicrobial effect.