Biocompatibility assessment of spark plasma-sintered alumina-titanium cermets.

Alumina-titanium materials (cermets) of enhanced mechanical properties have been lately developed. In this work, physical properties such as electrical conductivity and the crystalline phases in the bulk material are evaluated. As these new cermets manufactured by spark plasma sintering may have potential application for hard tissue replacements, their biocompatibility needs to be evaluated. Thus, this research aims to study the cytocompatibility of a novel alumina-titanium (25 vol. % Ti) cermet compared to its pure counterpart, the spark plasma sintered alumina. The influence of the particular surface properties (chemical composition, roughness and wettability) on the pre-osteoblastic cell response is also analyzed. The material electrical resistance revealed that this cermet may be machined to any shape by electroerosion. The investigated specimens had a slightly undulated topography, with a roughness pattern that had similar morphology in all orientations (isotropic roughness) and a sub-micrometric average roughness. Differences in skewness that implied valley-like structures in the cermet and predominance of peaks in alumina were found. The cermet presented a higher surface hydrophilicity than alumina. Any cytotoxicity risk associated with the new materials or with the innovative manufacturing methodology was rejected. Proliferation and early-differentiation stages of osteoblasts were statistically improved on the composite. Thus, our results suggest that this new multifunctional cermet could improve current alumina-based biomedical devices for applications such as hip joint replacements.

Peptide-functionalized zirconia and new zirconia/titanium biocermets for dental applications.

OBJECTIVE: Titanium materials have been functionalized with biomolecules as a modern strategy to incorporate bioactive motifs that will expand and improve their biomedical applications. Here, we have biofunctionalized biomaterials based on zirconia of much interest for dentistry: the widely used bioceramic 3Y-TZP and a newly developed 3Y-TZP/Ti biocermet. METHODS: The biosurfaces were activated, silanized, and functionalized with coatings made of oligopeptides. Surface activation by plasma or alkaline-etching was optimized. The surfaces were coated by tethering a purposely-designed RGD-containing peptide. We selected this oligopeptide as a model peptide to validate the effectiveness of the biofunctionalization process. Successful treatments after each step of the process were assessed by surface physical and chemical characterization with water contact angles and XPS, respectively. Coatings' stability was evaluated after 2h sonication in water. Pre-osteoblasts adhesion on the functionalized surfaces was also studied. RESULTS: 10-min air-plasma treatment effectively activated all types of materials with no detrimental effects on the material structure and hardness. Nitrogen XPS-peak confirmed that RGD-peptides were chemically-attached on the silanized samples. This was further confirmed by visualizing the functionalized surfaces with flourescence-labelled RGD-peptides before and after ultrasonication. Furthermore, RGD-functionalized surfaces significantly enhanced osteoblast adhesion on all types of substrates, which demonstrated their successful bioactivation. CONCLUSIONS: We successfully developed stable functional biocoatings on zirconia and biocermets made of oligopeptides. Surface bioactivation of zirconia-containing components for dental implant applications will enable their improved clinical performance by incorporating signalling oligopeptides to accelerate osseointegration, improving permucosal sealing, and/or incorporating antimicrobial properties to prevent peri-implant infections.

Osteoblastic cell response to spark plasma-sintered zirconia/titanium cermets.

Ceramic/metal composites, cermets, arise from the idea to combine the dissimilar properties in the pure materials. This work aims to study the biocompatibility of new micro-nanostructured 3 Y-TZP/Ti materials with 25, 50 and 75 vol.% Ti, which have been successfully obtained by spark slasma sintering technology, as well as to correlate their surface properties (roughness, wettability and chemical composition) with the osteoblastic cell response. All samples had isotropic and slightly waved microstructure, with sub-micrometric average roughness. Composites with 75 vol.% Ti had the highest surface hydrophilicity. Surface chemical composition of the cermets correlated well with the relative amounts used for their fabrication. A cell viability rate over 80% dismissed any cytotoxicity risk due to manufacturing. Cell adhesion and early differentiation were significantly enhanced on materials containing the nanostructured 3 Y-TZP phase. Proliferation and differentiation of SaOS-2 were significantly improved in their late-stage on the composite with 75 vol.% Ti that, from the osseointegration standpoint, is presented as an excellent biomaterial for bone replacement. Thus, spark plasma sintering is consolidated as a suitable technology for manufacturing nanostructured biomaterials with enhanced bioactivity.