Surface Nanostructures Enhanced Biocompatibility and Osteoinductivity of Laser-Additively Manufactured CoCrMo Alloys

Cobalt-chromium-molybdenum (CoCrMo) alloys are widely used in orthopedic implants due to their excellent corrosion and wear resistance and superior mechanical properties. However, their limited capability to promote cell adhesion and new bone tissue formation, poor blood compatibility, and risk of microbial infection can lead to implant failure or reduced implant lifespan. Surface structure modification has been used to improve the cytocompatibility and blood compatibility of implant materials and reduce the risk of infection. In this study, we prepared CoCrMo alloys with surface nanostructures of various aspect ratios (AR) using laser-directed energy deposition (L-DED) and biocorrosion. Our results showed that medium and high AR nanostructures reduced platelet adhesion, while all of the alloys demonstrated good blood compatibility and antibacterial properties. Moreover, the medium and high AR nanostructures promoted cell adhesion and spreading of both preosteoblast MC3T3 cells and human bone marrow mesenchymal stem cells (hMSCs). Furthermore, the nanostructure promoted the osteogenic differentiation of both cell types compared with the flat control surface, with a substantial enhancing effect for the medium and high ARs. Our study proposes a promising approach for developing implant materials with improved clinical outcomes.