Biocompatibility investigation of new generation alloys in simulated body fluid environment whose surface properties are modified via femto second laser

Nowadays, metallic implants are used to treat various bone and joint diseases. Stainless steel, Co-Cr alloys, Ti and Ti alloys are commonly used in orthopedic implants. In spite of their advantages, the biocompatibility and osseointegration of these metallic materials remain insufficient. Recently, among the new generation alloys, TiAlNb and high entropy TiTaHfNbZr alloys have come to attention as promising biomedical alloys owing to their biocompatible elemental content, similar elasticity with the bone tissue and biocompatibility. However, there aren't sufficient number of studies investigating their biocompatibilities. Moreover, in order to achieve the attachment of the bone tissue to these alloys in orthopedic applications, their surface properties should be improved. One of the most recent techniques used for the surface modification of metallic materials, femtosecond laser processing, draws attention among other surface processing techniques owing to its advantages such as providing homogenous surface topography while eliminating negative effects such as phase transformation, thanks to the very fast interaction of laser with the material. However, there are limited number of studies focusing on the femtosecond laser processing of new generation biomedical alloys to be used as biomaterials in the literature. With these motivations, in the first part of the current study, a preliminary biocompatibility investigation was conducted on TiAlNb alloy in simulated body fluid environment and it was deduced that Al ion release should be prevented via surface modification methods. In the second part of the current study, high entropy alloy TiTaHfNbZr alloy surfaces were processed via femtosecond laser in order to obtain various patterns with different repeating frequencies. The formed surfaces with different properties were characterized in terms of their wettability and surface energy which were followed by ex situ biocompatibility tests where the interaction of these surfaces with simulated body fluid and bioactivity were investigated for a biocompatibility evaluation in relation to surface properties.