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Diego Pedreira de Oliveira,1,* Tatiane Venturott Toniato,2 Ritchelli Ricci,2 Fernanda Roberta Marciano,3 Egor Prokofiev,4 Ruslan Z Valiev,4,5 Anderson Oliveira Lobo,6,* Alberto Moreira Jorge Júnior1,7,* 1Department of Materials Engineering, Federal University of São Carlos, São Carlos 13565-905, São Paulo, Brazil; 2Institute of Research and Development, University of Vale do Paraíba, São Paulo 12244-000, Brazil; 3Scientifical and Technological Institute, Brasil University, São Paulo 08230-030, Brazil; 4Saint Petersburg State University, Saint Petersburg 199034, Russia; 5Institute of Physics of Advanced Materials, Ufa State Aviation Technical University, Ufa 450000, Russia; 6LIMAV - Interdisciplinary Laboratory for Advanced Materials, Department of Materials Engineering, UFPI - Federal University of Piauí, Teresina 64049-550, Piauí, Brazil; 7University of Grenoble Alpes, CNRS, Grenoble INP-LEPMI, and SIMAP Labs, Grenoble 38000, France *These authors contributed equally to this work Background: Nanophase surface properties of titanium alloys must be obtained for a suitable biological performance, particularly to facilitate cell adhesion and bone tissue formation. Obtaining a bulk nanostructured material using severe plastic deformation is an ideal processing route to improve the mechanical performance of titanium alloys. By decreasing the grain size of a metallic material, a superior strength improvement can be obtained, while surface modification of a nanostructured surface can produce an attractive topography able to induce biological responses in osteoblastic cells. Methods: Aiming to achieve such an excellent synergetic performance, a processing route, which included equal channel angular pressing (ECAP), hot and cold extrusion, and heat treatments, was used to produce a nanometric and ultrafine-grained (UFG) microstructure in the Ti-6Al-7Nb alloy (around of 200 nm). Additionally, UFG samples were surface-modified with acid etching (UFG-A) to produce a uniform micron and submicron porosity on the surface. Subsequently, alkaline treatment (UFG-AA) produced a sponge-like nanotopographic substrate able to modulate cellular interactions. Results: After several kinds of biological tests for both treatment conditions (UFG-A and UFG-AA), the main results have shown that there was no cytotoxicity, expressed alkaline phosphatase activity and total protein amounts without statistical differences compared to control. However, the UFG-AA samples presented an attractive effect on the cell membranes, and cell adhesions were preferentially induced as compared with UFG-A. Both conditions demonstrated cell projections, but for UFG-AA, cells were more widely dispersed, and more quantities of filopodia formation could be observed. Conclusion: Herein, the reasons for such behaviors are discussed, and further results are presented in addition to those mentioned above. Keywords: SPD, ECAP, UFG Ti–6Al–7Nb alloy, implants, surface treatment, biological response |
