Wettability transition of superhydrophobic myristic acid/dodecyl mercaptan/Cu@ZIF-8/HA coating modified magnesium alloy driven by visible light for antibacterial and osteogenic applications

Abstract

Recently, superhydrophobic coating modified magnesium alloys are extensively utilized for anti-corrosion, anti-fouling and anti-bioadhesion fields due to their unique surface characteristics. However, lack of antibacterial and osteogenic properties have restricted the development of medical magnesium alloys for clinical implantation. Here, a facile superhydrophobic wettability transformation strategy is proposed to impart medical magnesium alloys with outstanding corrosion resistance, protection against bacterial infection and promotion of osteogenesis process. The copper (Cu2+)-doped zeolitic imidazolate frameworks-8 (ZIF-8) coatings were synthesized upon the surface of HA-modified Mg alloy via solvothermal method and then followed hydrophobic treatment in a mixed ethanol solution of dodecyl mercaptan (DDM) and myristic acid (MA) to obtain superhydrophobic properties. This particular superhydrophobic coating can be irradiated by visible light to make ligand-to-metal charge transfer produce photoelectrons and be captured upon the Cu@ZIF-8 coating surfaces as paramagnetic Zn2+ sites, and then generated reactive oxygen species which can scavenge off the reductive dodecyl mercaptan, thus converting to hydrophilic. This wettability transition allows for the regulation of implant surface properties according to the functional requirements of the implant at different clinical stages. Furthermore, the composite coatings modified Mg alloy after wettability transformation from superhydrophobic to hydrophilic can significantly kill pathogenic bacteria and promote osteoblast attaching behavior.