Nanostructured Ag⁺-substituted fluorhydroxyapatite-TiO₂ coatings for enhanced bactericidal effects and osteoinductivity of Ti for biomedical applications

Abstract

BackgroundPoor mechanical properties, undesirable fast dissolution rate, and lack of antibacterial activity limit the application of hydroxyapatite (HA) as an implant coating material. To overcome these limitations, a hybrid coating of Ag+-substituted fluorhydroxyapatite and titania nanotube (TNT) was prepared.MethodsThe incorporation of silver into the HA-TiO2 hybrid coating improves its antimicrobial properties. The addition of F as a second binary element increases the structural stability of the coating. The TNT/F-and-Ag-substituted HA (FAgHA) bilayer coating on the Ti substrate was confirmed by X-ray diffraction, scanning electron microscope, energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS).ResultsThe results indicate that the FAgHA/TNT nanocomposite coating has a dense and uniform morphology with a nano-rod-like structure. The solubility measurement result shows that the substitution of F− ions into the AgHA structure has a positive effect on the dissolution resistance of HA. The adhesion strength of FAgHA/TNT has significantly increased because of the interlocking of the roughened surface with nano-rod-like particles that entered into the voids of the TiO2 nanotubes. Compared with that of the bare Ti, the corrosion current density of FAgHA/TNT-coated Ti substrate decreased from 3.71 to 0.18 μA, and its corrosion resistance increased by almost two orders of magnitude. Moreover, despite pure HA, the FAgHA killed all viable Staphylococcus aureus after 24 hours of incubation. Although the fabricated FAgHA/TNT coating is hydrophobic, it induced deposition of the typical spherical apatite when immersed in a simulated body fluid (SBF); the osteoblasts spread very well on the surface of the coating. In addition, in vitro cell culture tests demonstrated cell viability and alkaline phosphatase (ALP) similar to pure HA, which indicated good cytocompatibility. Interestingly, compared with bare Ti, FAgHA/TNT-coated Ti surface was innocent for cell vitality and even more beneficial for cell osteogenesis in vitro.ConclusionEnhancing the osseointegration and preventing infection in implants, the FAgHA/TNT-coated Ti makes implants more successful.

Si, Sr, Ag co-doped hydroxyapatite/TiO2coating: enhancement of its antibacterial activity and osteoinductivity

“…XRD tests were used to examine the purity and crystalline structure. The phase compositions of the anodised samples were reported in our previous publications; 31,34 all the reections reproduced the standard patterns, including JCPDS#005-0682 for the Ti substrate and #021-1276 for rutile (Fig. 2c).…”

<p>Beneficial Effect of TaON-Ag Nanocomposite Titanium on Antibacterial Capacity in Orthopedic Application</p>

“…14 The biocompatibility of oxygen induction TaON-Ag nanocomposite thin films has been confirmed using an MTT assay, according to previous publications. 14,31 However, the osteogenic ability of Ag composite thin-film materials has been investigated in only a few studies. Li et al reported a Agembedded hierarchical TiO 2 film, which exhibited excellent bioactivity and cytocompatibility, as a promising candidate for orthopedic and dental implants.…”

Multisubstituted hydroxyapatite powders and coatings: The influence of the codoping on the hydroxyapatite performances

“…Similarly, Huang et al deposited hybrid coatings based on F − /Ag + co‐doped HAp and TiO 2 on Ti substrate by electrodeposition, obtaining nanostructured coatings composed of HAp without forming any other secondary phase. They demonstrated the obtainment of dense and uniform films with a surface of nanorods (diameters between 30 and 50 nm), characterised by enhanced HAp dissolution resistance, due to the fluorine incorporation and to the nanosized structure, and improved bonding strength.…”

“…Good osteoblasts morphology, adhesion, spreading and proliferation on doped coatings were demonstrated and, in particular, Zn/FHAp coatings were able to promote ALP expression, thanks to a simultaneous influence of nanostructured surface effects and ions release . Furthermore, Huang et al studied the biological properties of composite/hybrid coatings based on F/Ag co‐doped HAp and TiO 2 , in terms of cell viability and antibacterial features, highlighting improved biological activity and cytocompatibility, and a superior bactericidal effect against viable S aureus . In vitro cell tests were performed with MC3T3‐E1 cell line, confirming the material biocompatibility and no‐reverse effects on cell proliferation and osteoblastic differentiation, independently of Ag presence.…”