Nanostructured Ti–6Al–4V Reduces Adhesion of Several Bacterial Species: An In Vitro Study

Abstract

Biomaterial‐associated infections (BAIs) and insufficient early cellular response remain critical challenges for orthopedic implants. We introduce a comprehensive study that bridges current knowledge gaps by examining an early‐stage antimicrobial effect on the clinically relevant alloy Ti–6Al–4V. It combines pathogenic strains with parallel osteoblast assays and tilted‐view SEM analysis to obtain a qualitative understanding of the adhesion mechanisms. Detailed physicochemical characterization revealed a progressive increase in nanoscale roughness and oxide layer thickness, accompanied by selective Al/V depletion and pronounced hydrophilization. To evaluate biological responses, we used standardized in vitro models with Staphylococcus aureus, Staphylococcus epidermidis, and Escherichia coli. Bacterial adhesion was quantified by SYTO9 staining, a GFP‐expressing strain as a viability control, and SEM imaging. Nanostructured (Rq ≤ 40 nm) surfaces significantly reduced early bacterial attachment compared to polished nanoflat controls. In parallel, osteoblast‐like SaOs‐2 cells showed stable adhesion and spreading, confirmed by phalloidin/DAPI staining and LDH cytotoxicity assay. Together, these results demonstrate that NaOH‐etched Ti–6Al–4V surfaces can impair early microbial adhesion based on physical action and preserve osteoblast compatibility. By integrating advanced materials characterization with microbiological and cell biological assays, we provide a framework for topography‐driven surface design toward infection‐resistant orthopedic implants that support favorable early osteoblast–surface interactions.