Effect of Nanotextured Stainless Steel Surface Features on Antibacterial Properties and Osteoblast Activity In Vitro

Bacterial colonization and poor osteointegration are significant challenges for stainless steel implants. These issues often lead to implant-associated infections, localized tissue damage, and implant failure, which can result in chronic inflammation, osteomyelitis, the need for revision surgery, and delayed recovery. While nanotextured surface features have shown antibacterial activity and osteoblast proliferation, the specific role of surface feature size is not yet fully understood. Herein, we utilized an electrochemical technique to fabricate nanoprotrusion-like features on stainless steel surfaces, with distinct morphology and topography by varying the etching time at a fixed potential. The results show that etching time directly influences surface morphology, roughness, feature size, and depth profile. As etching time increases, nanoprotrusions initially become more pronounced, but extended duration leads to their reduction. These variations in feature size on nanotextured stainless steel surfaces reveal that larger nanoprotrusion sizes created from intermediate etching times exhibit greatest antibacterial activity, while also best promoting osteoblast proliferation, calcium deposition, and alkaline phosphatase activity in vitro. These distinct functions from the same nanotexture feature sizes provide key insights into designing next-generation stainless steel implants.