Jul 2026· Small Science· Vol 6· 0 citations· 62 references
Medicine
TL;DR
It is demonstrated that NaOH‐etched Ti–6Al–4V surfaces can impair early microbial adhesion based on physical action and preserve osteoblast compatibility, providing a framework for topography‐driven surface design toward infection‐resistant orthopedic implants that support favorable early osteoblast–surface interactions.
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.
Orthopedic implants face persistent clinical challenges of peri-implant infection and impaired osseointegration, especially in high-risk populations with trauma, osteoporosis, or diabetes. Herein, we report a coating-free strategy integrating three-dimensional (3D) printing and electrochemical anodization to fabricate porous titanium alloy implants with TiO2 nanotube (TNT) micro/nano hybrid surfaces. The TNT layer features tunable nanoscale dimensions. In vitro evaluations demonstrate that TNT surfaces exert diameter-dependent biological effects: small-diameter TNTs favor early human bone marrow mesenchymal stem cell (hBMSC) adhesion and proliferation, whereas large-diameter TNTs exhibit the strong antibacterial activity and potent osteogenic differentiation potential. Additionally, TNTs induce transient early M1 macrophage polarization, which synergizes with intrinsic contact-mediated antibacterial activity to accelerate pathogen clearance. Mechanistic investigations reveal that TNTs inhibit Staphylococcus aureus (S. aureus) adhesion and biofilm formation by downregulating topoisomerase I (TopA) to disrupt bacterial DNA topology homeostasis. For osteogenesis, TNTs modulate Filamentous actin (F-actin) cytoskeleton organization and XB130 adaptor protein expression in hBMSCs, thereby activating the PI3K/Akt/GSK3β/β-catenin signaling pathway to drive osteogenic differentiation. In vivo studies using rabbit femoral condyle models confirm that TNT implants exhibit markedly reduced bacterial burden in an infection model and enhanced bone-implant integration. Collectively, these results indicate that TNT 3D-printed titanium implants offer a synergistic platform combining antibacterial defense and enhanced osteointegration. This work provides a mechanistic understanding and preclinical validation for a clinically translatable surface-engineering strategy for next-generation orthopedic implants.
The multifunctional coating provides sustained antimicrobial activity alongside immunomodulatory and pro-regenerative effects, supporting its potential to treat implant-related infections while enhancing peri-implant soft tissue remodeling.
Mariana Martins Guerreiro, Amanda Paino Santana, D. M. Cunha et al.· Journal of Periodontal Resea...· 0 citations
OBJECTIVE
Stress shielding and bacterial infection are among the main challenges associated with metallic implants. To address these limitations, a Ti-35Nb-4Ag alloy was produced by powder metallurgy, combining a low elastic modulus (67.9 ± 1.1 GPa) with silver incorporated in solid solution to provide antibacterial activity.
METHODS
Compression testing was performed to determine the elastic modulus. Roughness, wettability, and surface free energy with its dispersive and polar components were determined. The cytocompatibility study was carried out in accordance with ISO 10993-5, using commercially pure grade 4 titanium as a control. Adhesion and proliferation studies were carried out with human fibroblast cells (hFFS) for 2, 4, 7, and 14 days. Antibacterial studies were performed on three Gram-positive bacterial strains: Streptococcus gordonii, Staphylococcus aureus, and Enterococcus faecalis. The colonies formed (CFU) and the metabolic activity were assessed.
RESULTS
The results showed that there were no statistically significant differences in roughness between the different metals tested. However, the Ti-35Nb-4Ag alloy had a lower contact angle (46°) than titanium (62°), and the surface energy was higher for the alloy (58 mJ/m²) than for titanium (41 mJ/m²). The increase in the polar component of the alloy (29 mJ/m2) compared to pure titanium (16 mJ/m2) was noteworthy. The alloy also showed enhanced fibroblast adhesion and proliferation while maintaining excellent cytocompatibility. In addition, the Ti-35Nb-4Ag alloy exhibited significantly lower CFU counts and bacterial metabolic activity than commercially pure titanium.
SIGNIFICANCE
The Ti-35Nb-4Ag alloy combines a low elastic modulus, favourable surface properties, good cytocompatibility, and antibacterial activity, making it a promising candidate for hard tissue replacement.
Matilde Roquette, Javier Gil, C. Aparicio et al.· Dental Materials· 0 citations
Implant‐associated infections remain a major challenge for stainless steel (SS) biomaterials because bacterial adhesion and biofilm formation can compromise clinical performance. This study investigated a hierarchical surface treatment for 316LVM SS combining cathodic plasma electrolytic oxidation (CPEO), acid etching (ET), and a copper‐based coating to improve antibacterial activity while preserving cytocompatibility. CPEO generated a microstructured oxide surface, acid ET introduced additional nanoscale features, and CuO deposition provided surface chemical functionalization. The modified surfaces were characterized in terms of morphology, roughness, wettability, surface chemistry, and electrochemical behavior, and their antibacterial and cytocompatibility performance were evaluated against
Staphylococcus aureus
and human dental pulp stem cells (hDPSCs). Among the tested conditions, the CPEO + ET + CuO surface showed the strongest antibacterial effect, reducing bacterial adhesion. Cell viability remained acceptable at the initial evaluation times, although a slight reduction was observed for the Cu‐containing layer on day 7, suggesting a time‐dependent response. Electrochemical tests showed that the surface modification route did not impair the corrosion resistance of 316LVM SS and, for some conditions, promoted improved corrosion behavior. These findings indicate that hierarchical texturing followed by a Cu‐containing layer is a promising strategy for improving the antibacterial performance of 316LVM SS while preserving cytocompatibility and corrosion behavior.
Tarciana D. Toscano, S. F. Brunatto, R. Torres et al.· Advanced Engineering Materia...· 0 citations
Additive manufacturing of Ti-6Al-4V implants enables patient-specific design, but process-induced surface and microstructural variations can strongly affect biological performance. In this work, Ti64 samples with varying volumetric energy densities (VEDs) were fabricated by selective laser melting to examine the combined effects of processing and surface modification on cell response and antibacterial behavior. The specimens were surface activated by controlled acid etching and coated with hydroxyapatite/reduced graphene oxide (HAp/rGO) composite via electrophoretic deposition. Surface morphology, chemistry, and porosity were assessed using Scanning Electron Microscopy, X-ray Photoelectron Spectroscopy, profilometry, micro-CT. Micro-CT showed higher internal porosity at lower VED, while a balance between densification and structural integrity was achieved at VED of 107 J mm- 3. In vitro cytocompatibility demonstrated >90% viability for all samples, meeting ISO 10993-5 requirements. Despite this, cell attachment depends on VED, the E63 condition exhibited the most uniform coverage after HAp/rGO coating, indicating an improved surface-cell interactions at lower VED. Antibacterial assays showed VED dependence; high-VED-E320 samples produced the highest biofilm formation even after coating, whereas low and intermediate VED conditions significantly reduced bacterial adhesion. Overall, biological functionality is observed to be governed by both coating and SLM parameters, with 107 J·mm- 3 offering the best combined structural, cytocompatible, and antibacterial performance.
Muhammad Usama Zaheer, Vahid Jahed, Rajveer Singh Rajaura et al.· Small· 0 citations
This study investigated microbiologically influenced corrosion (MIC) and passive-film degradation of a Ti-15Mo-3Al-2.7Nb-0.25Si β titanium alloy exposed to Pseudomonas aeruginosa. The alloy comprised a continuous β-Ti matrix with dispersed α-Ti precipitates, and this α/β dual-phase microstructure provided a potential microstructural basis for spatial variations in passivation behavior among different microregions. During immersion, P. aeruginosa formed a heterogeneous biofilm of bacterial cells and extracellular polymeric substances, altering interfacial mass transfer, oxygen distribution, and local chemistry. Relative to the sterile control, the inoculated group showed increases in maximum pit depth from 2.4 to 4.1 μm and corrosion current density from 8.72 to 17.2 nA cm−2, while the charge-transfer resistance decreased to 4.32 MΩ cm2 after 14 d, confirming enhanced localized corrosion. Mott-Schottky and XPS analyses showed that the donor density increased from 1.07 × 1019 to 1.29 × 1019 cm−3 and the Ti4+ fraction decreased from 72.29% to 66.74% and the relative Ti0 fraction increased from 7.01% to 17.59%, reflecting increased defect accumulation within the film, impaired passive-film integrity, and reduced local protective capability. P. aeruginosa therefore increases the MIC susceptibility of this β titanium alloy by biofilm-induced interfacial microenvironmental heterogeneity. These findings support MIC assessment and integrated antifouling-anticorrosion surface design for marine β titanium alloys.
Qingnan Zhang, Yuxin Tian, De Liu et al.· Metals· 0 citations
