Construction of Ag-incorporated coating on Ti substrates for inhibited bacterial growth and enhanced osteoblast response

In orthopedic fields, effective anti-infection property and promotive biocompatibility on surface of titanium implants are two crucial factors for long-term successful implants. Herein, Ag nanoparticles (NPs) loaded TiO2 nanotubes (TNT) arrays were fabricated on Ti substrates with assistance of ultraviolet irradiation. Then, bioactive multilayer films of chitosan (CHI) and dialdehyde alginate (ADA) pair were deposited onto the Ag-loaded TNT arrays via a layer-by-layer (LBL) self-assembly technique, which could effectively achieve the impactful antibacterial ability of titanium and endow the substrates with favorable biocompatibility, The driving force of the assembling of multilayer films came from two sources, electrostatic interaction and covalent interaction of Schiff-bonds between CHI and ADA. The surface topography and wettability of different samples were characterized by field emission scanning electron microscopy, transmission electron microscopy and contact angle measurements, respectively. In addition, Ag ions release from TNT-Ag and LBL substrate was measured via inductively coupled plasma atomic emission spectroscopy (ICP-AES). The results of a series of biological behaviors of osteoblasts on different substrates in vitro, including lactate dehydrogenase activity assay, cytoskeleton observation and cell viability measurement, confirmed that LBL substrates coated with (ADA-CHI)(10) multilayer films have negligible cytotoxicity and promote osteoblast growth compared with TNT-Ag substrates, which could ascribe to the slow-release of Ag ions and the biocompatibility of (ADA-CHI)(10) multi-layer. More importantly, owing to the release of Ag ions, the LBL samples still exhibited a prominent antibacterial activity for S. aureus and Era. Characteristics of bacterial adhesion and viability measurement proved that the fabricated Ag-incorporated platform was capable of obviously inhibiting the adhesion and growth of bacteria. Therefore, this approach of surface modification for Ti substrates presented here may provide an alternative strategy to simultaneously meet the desirable osteoblast growth and reduce bacterial infection for implants in clinical application.