Abstract
This study investigates the structure, mechanical, and antibacterial properties of tantalum‑copper nitride (TaCuN) coatings synthesized via reactive magnetron co-sputtering. Three variations of TaCuN films with increasing copper content were fabricated (TaCuN-1, TaCuN-2, and TaCuN-3). Comprehensive characterization of structure and mechanical properties was performed using confocal microscopy, XRD, XEDS, STEM, and nanoindentation, as well as evaluation of antibacterial activity and in vitro biocompatibility. The results revealed a compositionally stratified structure in the coatings, with sublayers exhibiting different ratios of Ta, Cu, and N. Surface morphology analysis exhibited the highest surface roughness in sample TaCuN-2. Mechanical testing revealed that TaCuN-1 exhibited the highest hardness and elastic modulus, with superior H/E and H 3 /E 2 ratios, indicating better resistance to cracking and plastic deformation. In contrast, TaCuN-3 demonstrated the greatest antibacterial activity, achieving a ∼ 97% reduction in Staphylococcus aureus after 24 h of co-cultivation, attributed to its elevated copper content and subsequent ion release. TaCuN-2 displayed intermediate structural and functional characteristics, suggesting a transition zone that balances mechanical robustness and biological performance. Antibacterial activity was attributed primarily to ion-mediated mechanisms, including membrane disruption and intracellular damage induced by released Cu ions. In vitro cytocompatibility tests confirmed that the coatings maintain acceptable biocompatibility within the investigated Cu range. These findings highlight the potential of tailored TaCuN coatings as multifunctional surfaces for biomedical applications, offering both enhanced mechanical integrity and effective antibacterial action.