The Effect of Surface Roughness and Hydroxyapatite Coating on the Biocompatibility of Co-Cr Alloys for Medical Implants

Background Cobalt-chromium (Co-Cr) alloys are extensively used in medical implants for their strength and corrosion resistance. However, improving their biocompatibility is essential to ensure better integration and performance in biological environments. This study investigates the effect of surface roughness and hydroxyapatite (HA) coatings on enhancing the biocompatibility and antimicrobial properties of Co-Cr alloys, aiming to create a durable, bioactive surface suitable for long-term implant use. Method Co-Cr alloy samples were prepared with varying levels of surface roughness achieved through grit-blasting with Al₂O₃ particles of different sizes (29 µm, 45 µm, 110 µm, and 250 µm). HA coatings were applied using a sol-gel spin-coating method to ensure even coverage and adhesion. The coated samples were analyzed using Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) for morphological and structural assessment. Biocompatibility and antimicrobial properties were evaluated through immersion in Simulated Body Fluid (SBF) and testing against Pseudomonas aeruginosa biofilm formation. Results HA-coated samples exhibited high homogeneity and adhesion, particularly on rougher surfaces (110 µm and 250 µm). SEM and XRD analyses confirmed enhanced stability and crystalline structure on roughened surfaces. Biological tests demonstrated that the HA-coated samples with higher roughness significantly inhibited Pseudomonas aeruginosa biofilm formation, indicating improved antimicrobial effectiveness. The samples also showed sustained stability in SBF, supporting their potential for long-term application in implants. Conclusion Surface roughness positively impacts the adhesion and effectiveness of HA coatings on Co-Cr alloys, enhancing biocompatibility and antimicrobial performance. HA-coated Co-Cr alloys with optimized roughness provide a promising solution for medical implants, offering both durability and infection resistance, crucial for long-term clinical applications.