Search

Biomimetic metallic biomaterials prepared for bone scaffolds have drawn more and more attention in recent years. However, the topological design of scaffolds is critical to cater to multi-physical requirements for efficient cell seeding and bone regeneration, yet remains a big scientific challenge owing to the coupling of mechanical and mass-transport properties in conventional scaffolds that lead to poor control towards favorable modulus and permeability combinations. Herein, inspired by the microstructure of natural sea urchin spines, biomimetic scaffolds constructed by pentamode metamaterials (PMs) with hierarchical structural tunability were additively manufactured via selective laser melting. The mechanical and mass-transport properties of scaffolds could be simultaneously tuned by the graded porosity (B/T ratio) and the tapering level (D/d ratio). Compared with traditional metallic biomaterials, our biomimetic PM scaffolds possess graded pore distribution, suitable strength, and significant improvements to cell seeding efficiency, permeability, and impact-tolerant capacity, and they also promote in vivo osteogenesis, indicating promising application for cell proliferation and bone regeneration using a structural innovation.

With the development of structural architectures, the demand for metamaterials with multiphysical characteristics has increased. The relationships between different properties, such as mechanical and mass-transport properties for bone scaffolds, are often mutually conflicting. Consequently, the optimization of these properties for metamaterials structured on the micro- to macroscale is challenging. In this study, inspired by the Hall–Petch relation, which indicates how one can independently tailor the strength and mass, we use a diamond configuration to construct microlattice metamaterials with decoupled mechanical and mass-transport properties to cater to artificial bone scaffolds. The elasticity and permeability are synchronously optimized using simple scaling laws. The results of compression experiments and transportation calculations demonstrate the promising performance of microlattices with an aspect ratio of 1 and at least 4 unit cells in the array direction. Furthermore, hierarchical microlattice metamaterials partitioned into spongy and compact zones are designed for bone scaffold applications. The proposed approach provides an innovative framework for developing multi-physics metamaterials for widespread engineering applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Rapid development in 3D printing technology has stimulated enthusiasm in the functional design of metamaterials with unique properties, in which multiple properties should be simultaneously optimized. However, this is challenging because different properties, such as mechanical and mass-transport properties, are often coupled strongly and cannot be adjusted independently. Herein, we propose an anisotropy-inspired and simulation-guided microlattice metamaterial design strategy that realizes independent tailoring of the elastic response and fluid transport performances. Diamond microlattice metamaterials are used for demonstration, constructed by using different facets ([001], [110] and [111]) and rotation degrees (15°/step), inspired from the atoms' arrangements. Through computational analyses, it is proven that the coupled relationship of mechanical and transport properties are abated and have directional dependence on crystal planes and orientation directions. Three microlattice metamaterials and a gradient microlattice metamaterial were fabricated by 3D printing for experimental verification. The assigned layer-by-layer deformation process and specific mass-transport characteristic of the gradient microlattice metamaterial were easily endowed. This study offers an approach to decouple synergy and enable separate tailoring for multi-physical metamaterials in a much larger performance regulation space, which can effectively guide simultaneous improvements toward practical applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Biomimetic metallic biomaterials prepared for bone scaffolds have drawn more and more attention in recent years. However, the topological design of scaffolds is critical to cater to multi-physical requirements for efficient cell seeding and bone regeneration, yet remains a big scientific challenge owing to the coupling of mechanical and mass-transport properties in conventional scaffolds that lead to poor control towards favorable modulus and permeability combinations. Herein, inspired by the microstructure of natural sea urchin spines, biomimetic scaffolds constructed by pentamode metamaterials (PMs) with hierarchical structural tunability were additively manufactured via selective laser melting. The mechanical and mass-transport properties of scaffolds could be simultaneously tuned by the graded porosity (B/T ratio) and the tapering level (D/d ratio). Compared with traditional metallic biomaterials, our biomimetic PM scaffolds possess graded pore distribution, suitable strength, and significant improvements to cell seeding efficiency, permeability, and impact-tolerant capacity, and they also promote in vivo osteogenesis, indicating promising application for cell proliferation and bone regeneration using a structural innovation., Competing Interests: We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work, there is no professional or other personal interest of any nature or kind in any product, service and/or company that could be construed as influencing the position presented in, or the review of, the manuscript entitled, “3D Printed Biomimetic Metamaterials with Graded Porosity and Tapering Topology for Improved Cell Seeding and Bone Regeneration”., (© 2022 The Authors.)