Recent advances in bio-functional Ta-based bone materials: materials design and bioactivity

Ta-based materials have gained significant interest for bioimplantable scaffolds because of their appropriate mechanical characteristics and biocompatibility. To overcome the serious limitation of bioinertness, there have been many efforts to enhance the bioactivity and osseointegration of Ta-based scaffolds through morphostructural and surface modifications. As scaffolds are implantable devices, sufficient bioactivity is needed to trigger the cellular functions required for tissue engineering. Consequently, a combination of materials and bioscience is needed to develop efficient Ta-based scaffolds, although reviews of this interdisciplinary field remain limited. This review aims to provide an overview of the main strategies to enhance the bioactivity of Ta-based scaffolds, describing the basic mechanisms and research methods of osseointegration, and the approaches to enhance bioactivity and osseointegration. These approaches are divided into three main sections: (ⅰ) alteration of the micromorphology, (ⅱ) customization of the scaffold structure, and (ⅲ) functionalization modifications (through alloying or the addition of surface coatings). Also provided are recent advances regarding biocompatibility assessment in vitro, osseointegration properties in vivo, and clinical trial results.