Preparation of hafnium nitride-coated titanium implants by magnetron sputtering technology and evaluation of their antibacterial properties and biocompatibility

Hafnium nitride (HfN) coatings with different thicknesses and various composition ratios were successfully fabricated on the surface of titanium alloys by magnetron sputtering, and their antibacterial properties and biocompatibility were evaluated. The structures of the coatings were characterized by X-ray diffraction (XRD; DX-2700BH diffractometer) in symmetric <i>θ</i>-2<i>θ</i> scanning mode. The surface morphologies of the coatings were characterized by scanning electron microscopy (SEM; Nova NanoSEM450). The surface element distribution of the film was characterized by the energy-dispersive spectrometer (EDAX ELECT PLUS). The antibacterial properties of different materials against <i>Staphylococcus aureus</i> (ATCC 25923) were evaluated by plate colony counting, crystal violet staining, SEM, and SYTO-9/PI live/dead bacterial staining. The proliferation of bone marrow mesenchymal stem cells was detected by CCK-8 assays, and the biocompatibilities of different materials were evaluated by calcein-acetoxymethyl/propidium iodide (PI) live/dead cell staining. The surface morphology and element analyses revealed that the HfN coatings and titanium substrates did not contain other substances, and their surfaces were relatively uniform. After 24 h incubated with <i>Staphylococcus aureus</i>, sample 2 (50 nm thick, N₂ flow rate of 2.5 sccm) displayed the best antibacterial performance. CCK-8 cell proliferation and calcein-AM/PI live/dead cell staining assays indicated that sample 2 had the best biocompatibility. The modified titanium implants had good biocompatibility and antibacterial properties. The results presented here can potentially guide and inspire additional ideas to alter the surfaces of titanium implants.