Optimization of tantalum–boron nitride coatings for enhanced biofunctionality in implant applications

The development of multifunctional implant coatings that promote biocompatibility while inhibiting bacterial adhesion is of critical importance in orthopedic and dental applications. In this study, Tantalum–Boron Nitride (Ta–BN) composite thin films were fabricated via dual-target magnetron sputtering at power levels of 15 W, 20 W, and 25 W, and their structural, biological, and antibacterial properties were evaluated. X-ray diffraction revealed amorphous structures for all coatings, while SEM confirmed dense, void-free morphologies. EDS showed a power-dependent compositional shift, with the 20 W group displaying the most balanced distribution (57.45% Ta, 32.55% B, 10.00% N). Biocompatibility testing with Saos-2 cells demonstrated the highest viability for the 20 W coating (91.3 ± 5.2%), closely approximating the control (100 ± 4.7%), whereas 15 W and 25 W coatings showed reduced values. Fluorescence microscopy further confirmed superior cell adhesion and uniform coverage on the 20 W surface. Antibacterial assays against E. coli revealed the strongest effect at 20 W, with bacterial viability reduced to 53.4 ± 4.2%, outperforming both 15 W (79.5 ± 6.3%) and 25 W (66.7 ± 5.1%). These results indicate that Ta–BN coatings deposited at 20 W offer the optimal balance of biocompatibility and antibacterial performance, making them strong candidates for next-generation implant surface modifications.