Synergistic impact of osseointegration and multifunctionality on functionally graded ceramic composites for bone healing applications

In this study, a functionally graded composite (FGC) sample was fabricated by layering five layers of hydroxyapatite (HA), silicon carbide (SiC), and copper oxide (CuO) nanoparticles. The osseointegration ability of all prepared FGC layers was assessed using simulated body fluid (SBF), and an investigation was performed using scanning electron microscopy (SEM). The physical, mechanical, electrical, and dielectric properties were evaluated before and after immersion in the SBF solution. Additionally, the antibacterial efficacy and biocompatibility of these layers were examined. Sintered layers exhibit porosity values ​​ranging from 5 to 10%, similar to compact bone, which is essential for effective osseointegration. SEM images showed good bioactive behavior across all FGC layers. The measured ultimate strength of the samples was 77.30, 81.54, 85.80, 93.29, and 102.82 MPa due to the successive increase in SiC and CuO content of the samples. This makes it mainly identical to cortical bone, sparing the bone from a stress-shielded effect. Soaking the produced layers with SBF did not impact their mechanical properties, indicating that their biological activity and mechanical properties are compatible. However, their electrical properties altered somewhat after soaking in SBF. Notably, the sample with the highest SiC and CuO content exhibited a 75% reduction in weight loss after applying a load of 10 N. Also, CuO inclusion in the studied layers led to a significant inhibition in S. aureus and E. coli bacterial growth up to 23 and 16 mm, respectively, without a noticeable cytotoxic effect. Based on these findings, the developed FGC sample and its layers are appropriate for bone healing applications.