(I-344) Exploring Highly Porous Scaffolds: An Alternative to Triply Periodic Minimal Surfaces for Bone Tissue Engineering

Introduction:: This study focuses on the design and evaluation of bone scaffolds produced using selective laser melting (SLM) for bone tissue engineering applications. The study compares two newly proposed modified face centered cubic (MFCC) scaffolds with tunable internal architectures to six distinct triply periodic minimal surface (TPMS) structures, which are categorized as sheet TPMS and skeletal TPMS types. The scaffolds are analyzed for mechanical, fluid flow, surface area, and surface curvature characteristics. Finite element method (FEM) and computational fluid dynamics (CFD) are employed to analyze the developed scaffolds. The scaffolds are fabricated using stainless steel 316L via SLM technology, and the produced scaffolds are subjected to mechanical testing. The results indicate that the MFCC scaffolds, with their customized internal architecture, exhibit comparable performance to TPMS scaffolds, while also providing potential advantages for bone scaffold applications. The study demonstrates the importance of key scaffold design characteristics, including stiffness, permeability, specific surface area, porosity, pore size, and local surface curvature. Overall, the developed MFCC scaffolds hold great promise for improving the performance and success rate of bone scaffolds, making them a potential alternative to TPMS scaffolds.

Materials and Methods:: The design, computational analysis, and fabrication of three different categories of scaffolds: MFCC, sheet TPMS, and skeletal TPMS are described in this section. Two types of MFCC scaffolds were studied: MFCC-1, where face pores are only connected to corner pores, and MFCC-2, where face pores are connected to both adjacent face pores and corner pores. The internal architecture of both MFCC types was tunable by varying face pore radius, corner pore radius, and unit cell edge length. All scaffold types had pore sizes within the recommended optimum range for bone cell ingrowth, and scaffolds with 75%, 80%, and 85% porosities were designed, analyzed, and fabricated by Selective Laser Melting (SLM). FEM and CFD were used to evaluate the mechanical and fluid flow properties of the scaffolds, respectively. MATLAB code was generated to analyze the local curvature of the scaffold surfaces. FEM was used to simulate scaffold compression, and CFD was used to evaluate permeability. The available surface area for cell adhesion was determined by specific surface area, and the amount of concavity of the scaffold surfaces was determined by studying local curvatures. The section provides detailed information about the methods used to design, analyze, and fabricate the scaffolds.

Results, Conclusions, and Discussions:: The study aims to compare three different scaffold designs - MFCC, sheet TPMS, and skeletal TPMS - based on various aspects such as mechanical properties, fluid flow behavior, surface area, surface curvature, and printability. The findings are analyzed to evaluate the performance of these scaffold designs and identify the potential of MFCC scaffolds as an alternative to TPMS structures. The results reveal that MFCC scaffolds cover a wide range of scaffold characteristics and can achieve permeability and specific surface area values that span nearly the entire range of these characteristics for natural bone tissue. The mechanical and biological performance of a scaffold is directly influenced by its stiffness, permeability, and specific surface area. In addition, the study includes von Mises stress, fluid velocity field, and pressure drop distribution for all eight types of scaffolds that were studied to better illustrate the impact of the internal architecture of the scaffolds on their mechanical and fluid flow properties. From the analysis, it is observed that the distribution of stress through the scaffold structure varies depending on the scaffold design category, and MFCC scaffolds have a relatively uniform distribution of loads across the scaffold structure. In terms of permeability, the greatest fluid velocities occur in structures with smaller internal channels. Moreover, pressure drop analysis demonstrates that sheet TPMS scaffolds with convoluted internal surfaces have the highest pressure drop, while solid TPMS scaffolds with less obstructive internal architecture demonstrate the lowest pressure drop, and the pressure drop in MFCC scaffolds is intermediate. Based on the results of this study, MFCC scaffolds can be considered as an alternative to TPMS scaffolds because a wide range of mechanical and fluid flow properties are achievable by MFCC scaffolds which span the whole range obtained for natural bone tissue.

Acknowledgements (Optional): :

References (Optional): :