Silver-Releasing Micro-/Nanoporous Coating on Additively Manufactured Macroporous Ti-Ta-Nb-Zr Scaffolds with High Osseointegration and Antibacterial Properties

Abstract

The two major problems of titanium alloy surface of bone/dental implants were the lack of native tissue integration and associated infection. To solve these problems, the development of self-defending implants with intrinsic osteogenic properties has been highlighted, in which titanium alloy surfaces of bone/dental implants are endowed with antibacterial property by silver (Ag) incorporated in biomaterials. In this study, we biofunctionalized the surface of selective laser melting (SLM) manufactured volume-porous Ti-Ta-Nb-Zr scaffolds by using plasma electrolytic oxidation (PEO) as a way to eliminate the peri-operative bacterial load and promote osseointegration. In the experiment, the PEO process operated with three different concentration (1, 1, and 2 g/L) of a AgNO3 solution. As a result, a titanium oxide coating embedded with calcium and phosphorous and Ag was formed by one-step PEO treatment, and a presence of HAp was detected by X-ray diffraction (XRD) and XPS. In addition, Ag ions were found to be released from the scaffolds for at least 28 days, resulting in an effective prevention of bacterial adhesion and a decrease of the number of planktonic bacteria, with no sign of cytotoxicity shown simultaneously. Highly porosity micropores were formed on the surface of scaffolds after oxidation, and the mechanical properties did not show any signs of change. Besides, a strong calcium deposition and osteoconductive effect were found on the surface of PEO-treated Ag scaffolds. To sum up, this study reveals the potential of PEO coatings to biofunctionalize SLM Ti-Ta-Nb-Zr scaffolds with antibacterial agents. The biomaterials developed here, therefore, exploit the biofunctionalized behavior of Ag to offer strong antibacterial behavior and osteogenic promotion without cytotoxicity of Ag against mammalian cells.

A Comprehensive Review of Surface Modification Techniques for Enhancing the Biocompatibility of 3D-Printed Titanium Implants

“…Despite some cellular toxicity associated with Ag + , its toxicity can be minimized through combination with other methods. Wu et al [119] modified the surface of 3D-printed implants using plasma PEO and added Ag+ to enhance antimicrobial properties. The coating demonstrated significantly improved antimicrobial performance and bone integration capability without toxicity.…”

In vitro application of drug-loaded hydrogel combined with 3D-printed porous scaffolds

“…Ti-10Ta-2Nb-2Zr powder, with a particle size of 15-70 µm, was used with a spherical shape, which we presented elsewhere [29,30,33].…”

Mechanism of tetraborate and silicate ions on the growth kinetics of microarc oxidation coating on a Ti6Al4V alloy

“…Recently, a multi-functional composite coating with antibacterial and biological activities was obtained by doping Ca, P, Sr, Zn, and Ag into MAO coating. [3][4][5][6] The wear resistance of the coating was improved by doping graphite, MoS 2 , PTFE, Al 2 O 3 , Si 3 N 4 , and Si. 3,[7][8][9] The thermal emissivity was regulated by doping V, W, Fe, Co, Ni, and Zr, 10,11 and the catalytic activity was improved by doping Tb, Ag, ZnO, WO 3 , FeO, and G-C 3 N 4 .…”

“…[3][4][5][6] The wear resistance of the coating was improved by doping graphite, MoS 2 , PTFE, Al 2 O 3 , Si 3 N 4 , and Si. 3,[7][8][9] The thermal emissivity was regulated by doping V, W, Fe, Co, Ni, and Zr, 10,11 and the catalytic activity was improved by doping Tb, Ag, ZnO, WO 3 , FeO, and G-C 3 N 4 . [12][13][14][15] The MAO mechanism is more complex than anodic oxidation or other surface treatment techniques.…”