Synthesis and characterization of TiO₂-ZnO composite thin films for biomedical applications

Titania (TiO₂) has superior biocompatibility, while zinc oxide (ZnO) is antibacterial. This investigation aimed to study the influence of TiO₂-ZnO composite films on enhancing the biocompatibility of stainless steel (SS). Radio-frequency magnetron sputtering (RF-MS) technique is used to synthesize TiO₂-ZnO composite thin films on 304-SS substrates from three sputtering targets with typical chemical compositions of 100% TiO₂, 90%TiO₂-10%ZnO, and 75%TiO₂-25%ZnO, mixed by their respective weight percentages. The influence of surface chemistry, morphology, and wettability of TiO₂-ZnO composite film on its osseointegration and antifouling characteristics was studied. The biocompatibility was assessed by protein adsorption kit, cytotoxicity assay, and cell adhesion of MG63 osteoblast cells, followed byS. aureusbacterial adhesion studies. All RF-MS films displayed hydrophobicity, minimal bacterial-cell adhesion, and higher cytocompatibility than the SS. RF-MS films deposited from the 75%TiO₂-25%ZnO target exhibited the highest antifouling capability due to the least protein adsorption and the highest antibacterial ZnO concentration. However, increased ZnO concentration decreased MG63 cell viability. RF-MS films deposited from the 90%TiO₂-10%ZnO target showed the highest mammalian cell viability of ≈88% and attachment. High plasma protein adsorption caused decreased mammalian cell viability and higher bacterial adhesion on 100% TiO₂film and SS. Biocompatible and antifouling TiO₂-ZnO composite thin films on SS substrates offer an alternative to conventional antibiotic coatings to combat antimicrobial resistance (AMR) and biofilm-related infections.