Antibacterial modification of the marginal layer by silver-integrated ED-Machining of TiAl6V4-implant material – AbakSi

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The increased demand for joint implants has led to an increased incidence of periprosthetic joint infections, which are frequently caused by bacteria of the Staphylococcus spp. family. The currently used antibiotic therapy is mainly effective in the immediate phase after implantation. In order to long-term prevent bacterial infections, solutions for a long-lasting antibacterial effect need to be established. The employment of silver on the implant surface is a possible solution.In this project, it will be investigated how silver can be deposited into the marginal layer of the implant during the machining process by electrical discharge machining (EDM) with silver nanoparticles mixed in the dielectric (Powder-mixed EDM - PMEDM). A continuous and relatively thin alloy layer (≈ 2.5 µm), which is enriched with silver among others, has been generated in preliminary investigations and evaluated with regards to its antibacterial effect. A significant reduction of the Staphylococcus aureus bacterial numbers and clusters has been achieved at a 3.78% silver content, while a significant increase of osteoblasts in the range from 0% to 4.84% silver content has been observed. However, the homogeneity of silver deposition in the modified layer poses a major challenge facing PMEDM for implant applications. In addition, the efficiency of the antibacterial-biocompatible properties of the modified surfaces must be evaluated over a longer period of time.Therefore, the overall objectives of the project are to master the PMEDM process for the targeted generation of the defined modified layer and to gain a deeper understanding of the antibacterial-biocompatible effect of Ti-6Al-4V implant surfaces enriched with silver. The central approach of the research is the uniform distribution of silver nano-particles in PMEDM machining gap by applying an optimal flushing strategy with the support of multi-physics simulations and ultrasonic vibration. Furthermore, the long-term properties of the modified surface generated by PMEDM will be evaluated with regards to antibacterial effects and biocompatibility.