Synergistic effects of osseointegration and multifunctional properties: Mechanical and electrical performance of functionally graded ceramic composites before and after soaking in SBF for bone healing applications

This work presents the creation of functionally graded composite (FGC) intending to enhance bone healing, as traditional bone repair materials typically do not possess the necessary qualities for perfect healing. In this context, the FGC was fabricated by layering five layers of hydroxyapatite (HA), silicon carbide (SiC), and copper oxide (CuO) nanoparticles. Analysis was conducted using characterization techniques such as X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). Furthermore, the osseointegration ability of all prepared FGC layers was assessed using simulated body fluid (SBF) and investigation by FESEM. The physical, mechanical, electrical, and dielectric properties were measured before and after soaking in the SBF solution. Additionally, the antibacterial effect and biocompatibility of these layers were evaluated. Sintered layers exhibit porosity values ​​ranging from 5–10%, similar to compact bone, which is essential for effective osseointegration. FESEM images showed good bioactive behavior across all FGC layers. Increasing the proportions of SiC and CuO improved the compressive strength to match cortical bone, reducing compression shielding. In addition, these additives significantly enhanced electrical conductivity and reduced dielectric properties, which are vital factors for bone regeneration. Significantly, soaking the prepared layers with SBF did not affect the mechanical properties, which indicates that there is no conflict between the biological activity of these layers and their mechanical properties. However, their electrical and dielectric properties changed slightly due to their soaking in the SBF solution. Notably, the sample with the highest SiC and CuO content exhibited a 75% reduction in weight loss. Importantly, CuO inclusion led to a considerable improvement in the antibacterial efficacy of the FGC layers without a noticeable cytotoxic effect. These findings indicate that the prepared FGC and its layers have promising multifunctional performance and are a suitable candidate for bone healing applications.