Leveraging 3D Printing-Induced Spherulitic Topographical and Biochemical Cues on Polyether Ether Ketone/Hydroxyapatite/Magnesium Orthosilicate Composites for Orthopedic Applications

A prime focus in orthopedic research is to promote osseointegration, while improving the functionality of implantable biomaterials. Surface topographic features have been shown to influence cell-biomaterial interactions, thereby facilitating cell adhesion, proliferation, and growth. However, a key challenge lies in inducing such topographical cues through existing biofabrication technologies. This study presents a newer strategy to leverage existing 3D printing (3DP) technology, promoting topographical cues manifested as microscopic spherulitic crystals integrated with nanoscopic lamellas on printed surfaces. Poly ether-ether-ketone (PEEK) composites reinforced with hydroxyapatite (HAp) and magnesium orthosilicate (Mg₂SiO₄) are printed using droplet-based 3D printing (3DP) technology, wherein the printing parameters are tailored to induce a network of spherulitic topographical cues in conjunction with biochemical cues arising from exposed bioactive fillers. Human osteosarcoma (Saos-2) cells are used to investigate the synergistic influence of the topographical and biochemical cues on the cell-material biological interactions. The composites exhibit hydrophilic surfaces with enhanced surface energy, promoting cellular adhesion and the formation of numerous filopodia, indicating an active engagement with spherulitic topographies. Composite surfaces featuring spherulitic topographical and biochemical cues foster a conducive environment, augmenting the cytocompatibility and osteogenic capabilities. Furthermore, process optimization not only improves the mechanical performance of the composites but also enhances their damping capabilities, a critical attribute for implant applications. This approach demonstrates that engineered spherulitic-topographical cues, in conjunction with biochemical cues, can mimic lamellar bone morphology, yielding improved biological and dynamic mechanical responses and highlighting their potential for personalized orthopedic implant applications.