Electrophoretic deposition of TiO₂ nanotubes and antibiotics on polyurethane coated stainless steel for improved antibacterial response and cell viability

In the quest for advancing the performance of metallic implants, surface modification emerges as a pivotal strategy to mitigate ion depletion, enhance the host's biological response, and exhibit anti-microbial behavior with reduced cytotoxicity. In this study, we developed a non-traditional electrophoretic deposition (EPD) hybrid coating for medical-grade stainless steel 316 L (SS316L) surfaces covered with a segmented polyurethane (SPU). These coatings are composed of anatase TiO₂ nanotubes (TiO₂_A), and antibiotics (nisin N or gentamicin G). We characterized the modified metals using FTIR and Raman spectroscopy, contact angle measurements, AFM, TGA, SEM-EDX, as well as assessing their antimicrobial response and cell cytotoxicity. The results demonstrate the formation of porous surfaces with embedded nanotubes and antibiotics within and on the polyurethane surfaces. Samples with SPU+ TiO₂_AG EPD exhibited superior coverage, antimicrobial properties, and enhanced viability compared to cases where only particles or antibiotics were coated individually. Additionally, samples of SPU+ TiO₂_AN EPD displayed favorable hydrophilicity and suitable cytotoxicity. Therefore, the synergistic effect of nanoparticles and antibiotics positively influences the functionality of the coating