Surface modification of β-type Ti–13Nb–7Sn–4Mo alloy by Sr and Ag incorporation into CaTiO3/anatase nanotubes for antibacterial and cell proliferation enhancement

Abstract

To address the persistent challenges of implant-associated infections and insufficient osseointegration, this study presents a surface modification strategy for low-modulus Ti–13Nb–7Sn–4Mo alloy. In this approach, titania nanotube arrays were prepared by anodization and microwave annealing. A CaTiO₃/anatase hybrid structure was then formed hydrothermally, followed by Sr and Ag incorporation to enhance cell response and antibacterial function. Transmission electron microscopy analysis revealed that CaTiO₃ particles were primarily distributed on the nanotube surface and partially extended into the nanotube interiors. Selected area electron diffraction and high-resolution TEM confirmed the formation of Ca_(1–x)Sr_xTiO₃, indicating partial substitution of Ca by Sr. In addition, Ag nanoparticles with uniform distribution on and within the nanotube arrays were identified by TEM-SAED analysis. Antibacterial assays using Staphylococcus aureus and Escherichia coli demonstrated that the sample with 0.58 at.% Ag achieved an antibacterial activity value (R) greater than 2.0, corresponding to a bacterial reduction rate exceeding 99%, indicating effective antibacterial performance. These findings highlight the critical role of surface Ag content in antibacterial efficacy. Furthermore, in vitro culture of MG63 osteoblastic cells confirmed that the hierarchical surface morphology—including micron, submicron, and nanoscale features—facilitated strong cell adhesion and proliferation.