Micromechanical Behavior of TPMS Scaffolds for Bone Tissue Engineering

Abstract

The triply periodic minimal surfaces (TPMS) methodology is explored to design porosity and curvature‐controlled tissue engineering (TE) scaffolds. This work combines mechanical testing and finite element (FE) simulation to characterize TPMS scaffolds micromechanical behavior, i.e., to estimate the response at the cell level to the macromechanical properties of different geometries (Schwartz D, Gyroid, and Schwartz P, with 60%, 70%, and 80% porosity, identified from SD60 to SP80) and testing conditions (6%, 8%, and 10% ramp compression, during 10, 20, and 30 s). Mechanical tests with ten 3D printed samples per model obtain Young Modulus levels from 0.048 GPa (SD80) to 0.267 GPa (SD60) and yield stresses from 0.495 MPa (SP80) to 5.226 MPa (SD60), being these associated with trabecular bone. FE simulations identify strain rate as the major influencer for cell response, as the probabilities for bone formation increase from 23.18% (SD) to 29.81% (SP) when increasing the compression period from 10 to 30 s. Additionally, compression beyond 6% causes excessive rates of cell death. SD and SG models have more consistent cell adhesion paths than SP ones, but superior stiffness of SD scaffolds induces higher cell death probabilities. Thus, SG scaffolds would be a better choice for most TE applications.

Porous Geometry Guided Micro-mechanical Environment Within Scaffolds for Cell Mechanobiology Study in Bone Tissue Engineering

“…Porosity is also the main determinant for the amount of strain in the scaffold when an external force is applied according to both micro-FE analyses and experimental characterisation ( Hannink and Arts, 2011 ; Castro et al, 2020 ). If under pressure/compressive force loading through bioreactors, a scaffold with a lower porosity (i.e.…”

“…Under mechanical compression, the pore shape can have a distinct influence on the overall structural stiffness of the scaffold ( Castro et al, 2020 ; Jahir-Hussain et al, 2021 ). According to their calculations, the triangular pore shape resulted in the highest structural stiffness of the scaffold and the spherical pore shape resulted in the lowest stiffness among the various pore shapes (spherical, cubic, hexagonal and triangular).…”

Challenges in computational fluid dynamics applications for bone tissue engineering

“…Permeability has been demonstrated to be essential for cellular growth, with more permeable scaffolds generating more favourable conditions [10]. However, it should be highlighted that high permeability scaffolds also present some limitations, namely, lower overall mechanical properties and the reduction of the cell–scaffold interaction [11]. This is because high permeability is normally caused by high porosity, which might not allow sufficiently long entrapment of the cells inside the scaffold.…”

“…Studies have shown that, during the scaffold design process, small changes to the pore size and/or porosity might considerably influence the scaffold's mechanical support and the process of cell growth and tissue infiltration [10,11]. Other factors that might also influence scaffold properties are the materials and manufacturing techniques that are chosen [12,13].…”

Evaluating Directional Dependency of Selective Laser Sintered Patient Specific Biodegradable Devices to Improve Predictive Modeling and Design Verification

“…In addition to structural analysis, a number of computational methods have been applied to simulate and predict mechanical performance, permeability and tissue formation in 3D printed tissue engineered devices. 1,4,8,16,23,26 Additionally, computational mechanical tests can contribute to the design verification phase of the patient specific device design control development process. 15 Predicting the mechanical performance of a design is dependent on intrinsic properties of materials used in the manufacturing process as well as the specific manufacturing process.…”