Electrochemical nanostructuring of surfaces of bulk metallic glasses on Ti-Cu basis for improvement of their biocompatibility

• Applicants: Dr. Annett Gebert; Dr. Juliane Salbach-Hirsch
• Subject Area: Biomaterials ; Coating and Surface Technology
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 458057521

Bulk metallic glasses (BMG) on Ti-Cu basis are promising new materials for bone implants in orthopedics, trauma and dental surgery, mainly due to their high mechanical biofunctionality. But in comparison to present clinically used materials their biocompatibility is still insufficient. A main goal of present research activities is therefore, the development of concepts for surface modifications at the nanoscale which meet the present requirements on multi-biofunctionality. In the first project period, electrochemical (anodic) processes for the growth of nanoporous oxide layers on the BMG surface with simultaneous depletion of Cu-species from near-surface regions were developed. These act effectively passive with complete suppression of critical pitting corrosion in (normal) physiological media. The mechanical properties are not deteriorated by those grown oxide layers and the cytocompatibility is improved. On basis of the results obtained so far, the planned project aims at the development of nanoscale layer systems on Ti-Cu- based bulk metallic glasses for further improving their biocompatibility. Two promising bulk glass-forming Ti-Cu-based alloys which are established at IFW Dresden regarding different synthesis routes, will be investigated. Using the nanoporous oxide states as interlayers, further biofunctional layers will be generated by chemical and electrochemical coating techniques. The related reactions mechanisms as well as layer – property relations will be described. The focus will be on clarifying the effects of the surface state of the metastable glass substrate on the respective initial nucleation and layer growth processes und, the resulting morphology, thickness, crystallinity and adhesion of the individual coatings. The developed layer systems shall exhibit a high corrosion resistance even under aggressive inflammatory physiological conditions. Further, they shall improve the wear properties of the BMG surfaces. In cell biological studies, the cell-mediated interactions with the modified metallic glass surfaces will be investigated. The ALD oxide layers offer defined chemical and topographical surface properties which can promote the adhesion, viability and differentiation of osteoblasts. It will be analyzed, to which extend dissolved materials fractions and different surface states influence the cell-mediated signaling and how they can contribute to bone formation by modulation of pro-osteogenic cytokines. The cytocompatibility and potential immunomodulatory effects will be evaluated in mono and coculture systems with osteoblasts and osteoclasts under standardized conditions.

• DFG Programme: Research Grants
• Co-Investigator: Professorin Dr.-Ing. Martina Zimmermann