In vitro degradation and photo-stimulated antibacterial activity of 2D-co-3D MOFs coating on AZ31 magnesium alloy
Magnesium alloys are promising biodegradable bone implant materials due to their biocompatibility and mechanical compatibility, but rapid degradation and postoperative bacterial infection limit clinical application. Here, zeolitic imidazolate framework-8 (ZIF-8) and 3,4,9,10-perylenetetracarboxylic diimide (PD) composite coatings (ZIF-8@PD) were fabricated in situ on micro-arc oxidation (MAO) coated AZ31 alloys via two-step and one-step (OS) methods. The MAO/ZIF-8@PD and MAO/ZIF-8@PD (OS) coatings reduced corrosion current density by three and two orders of magnitude, respectively, compared to MAO coating, due to the physical barrier of the 2D-co-3D MOF structure. Under 808 nm near-infrared laser irradiation, photothermal and photodynamic effects from PD, combined with contact killing by released Zn2+ ions, achieved bactericidal rates ≥99.5% against E. coli and S. aureus. Photothermal conversion efficiencies were 44.01% and 48.57% for the two-step and one-step coatings, respectively. The distinct Zn2+ sources led to different 2D-co-3D MOF structures, influencing degradation and antibacterial behavior. These coatings offer a strategy to enhance corrosion resistance and antibacterial activity of Mg alloys for biomedical applications.