Malfunctions in Medical Implants Explained

Martina Cihova, an Empa researcher, is delving into the world of titanium implants to investigate the effects of surface treatments on their durability and biocompatibility within the human body.

Many medical devices, such as artificial joints, dental implants, and pacemakers, are made of titanium. However, the ultra-thin native oxide layer on their surface, typically less than ten nanometers thick, often receives insufficient attention in medical technology. Cihova's research highlights the importance of understanding this layer's behavior at the interface with human tissue to explain implant failures and rejections.

Cihova's research project aims to investigate the impact of surface treatments on the crystal forms of titanium oxides and their interactions with the human body. Manufacturers sometimes alter the oxide layer on titanium implants for various purposes, such as color-coding or promoting bone growth. Cihova's findings could contribute to developing safer and more stable implants by improving material design and surface treatments to enhance biocompatibility and longevity.

The research will investigate how the biointerface behaves in contact with proteins like fibrinogen and living macrophage cells. Cihova's team creates model substrates with differently structured titanium oxide layers to systematically vary in heterogeneity. The substrates are exposed to increasing complex body fluids to investigate the fundamental relationships between structure, properties, and reactivity of oxides.

Cihova's research starts with simulated physiological fluids containing only water and ions, and progressively adds proteins and living cells. The research includes investigating interfaces using electrochemical methods combined with high-resolution electron and atomic force microscopy.

An atomic force microscope image shows distinct areas with different surface potential on titanium oxide, created by laser-induced changes in the structure. Cihova is concerned about the potential effects of these surface treatments on the implant's interaction with the body and its corrosion resistance.

Cihova's research project has been funded by an "Ambizione-Grant" from the Swiss National Science Foundation. She is thrilled that she's been able to enthuse colleagues from all three Empa sites for this project, enabling an interdisciplinary approach. Cihova plans to extend these methods to other medical materials following her 'Ambizione' project in 2028.

Cihova is convinced that this research field will gain even more importance in emerging areas like nanomedicine or implantable sensors. She hopes that findings in the coming years will lead to safer and more stable implants. Today, patient-specific implants can be 3D-printed using laser methods, and understanding the behavior of the native oxide layer on their surface could lead to even more personalized and effective medical devices.