Sol–gel-assisted micro-arc oxidation synthesis and characterization of a hierarchically rough structured Ta–Sr coating for biomaterials

Tantalum (Ta) is an element with high chemical stability and ductility that is used in orthopedic biomaterials. When utilized, it can produce a bioactive surface and enhance cell–material interactions, but currently, there exist scarce effective methods to introduce the Ta element onto the surface of implants. This work reported a sol–gel-assisted approach combined with micro-arc oxidation (MAO) to introduce Ta onto the surface of the titanium (TC4) substrate. Specifically, this technique produced a substrate with a hierarchically rough structured topography and introduced strontium ions into the film. The films were uniform and continuous with numerous crater-like micropores. Compared with the TC4 sample (196 ± 35 nm), the roughness of Ta (734 ± 51 nm) and Ta–Sr (728 ± 85 nm) films was significantly higher, and both films (Ta and Ta–Sr) showed increased hydrophilicity when compared with TC4, promoting cell attachment. Additionally, the in vitro experiments indicated that Ta and Ta–Sr films have the potential to enhance the recruitment of cells in the initial culture stages, and improve cell proliferation. Overall, this work demonstrated that the application of Ta and Ta–Sr films to orthopedic implants has the potential to increase the lifetime of the implants. Furthermore, this study also describes an innovative strategy to incorporate Ta into implant films.