Mimicking Cortical Bone-Like Properties Using SLM-Printed Schwarz Diamond-Based Walled Triply Periodic Minimal Surface Cellular Structures

Abstract

Cellular structure-based materials represent one of the most emerging themes in additive manufacturing of orthopedic implants. This has been more relevant as natural bone possesses a unique porous architecture, which cannot be mimicked in conventional manufacturing. In this perspective, the present study focuses on selective laser melting of Schwarz diamond-based triply periodic minimal surface (TPMS) structures in Ti6Al4V while varying unit cell size from 2.5 to 3.0 mm. The extensive micro-computed tomography analysis established that the SLM-based optimised process parameters enabled good dimensional tolerance and manufacturability of the TPMS structures. An impressive combination of the compressive elastic modulus (14-20 GPa), tensile elastic modulus (38 - 60 GPa), compressive strength (413-547 MPa), and tensile strength (95-450 MPa), together with a unique 3D microstructure, closely resembles the properties of human cortical bone. A linear correlation between strength/modulus with 3D pore architectural parameters (size, tortuosity) was recorded. Cell culture results demonstrated strong MC3T3-E1 pre-osteoblast adhesion and proliferation on the TPMS structures. The confocal microscopy observations revealed the cellular bridging, migration, and colonisation, indicating excellent cytocompatibility and signatures of osteogenesis.

Keywords: Triply periodic minimal surface, Bone-mimicking, Pore architecture, Osteogenesis