Abstract Tissue engineering scaffolds, as artificial substrates for cell growth an‎d frameworks for the repair of damaged bones, play a crucial role in the success of bone regeneration treatments. The performance of these scaffolds simultaneously depends on their stiffness an‎d their ability to effectively facilitate material transport. The geometric structure an‎d porosity percentage of scaffolds are the most important parameters determining their stiffness an‎d mass transfer capability. The aim of this study is to investigate the effect of structural geometry an‎d porosity percentage in various types of bone scaffolds on their mechanical an‎d biological properties. In this research, six different porous structure models including Voronoi, TPMS, IsoTruss, Octet, Truncated Cube, an‎d Weaire-Phelane structures with porosities of 60%, 70%, an‎d 80% were examined. The target structures were modeled using nTop design software. To eva‎luate stiffness, scaffold samples were fabricated using a fused Deposition Modeling (FDM) 3D printer with polylactic acid plus (PLA+) filament an‎d subjected to compression testing. Additionally, to analyze mass transfer, the diffusion an‎d movement of nutrients within the scaffolds were simulated using COMSOL Multiphysics software. The quantitative parameter for assessing mass transfer capability was the pressure dro‎p along the fluid pathway within the scaffold, while the elastic modulus was used to eva‎luate mechanical stiffness. The results showed that increasing porosity improved permeability an‎d mass transfer in the scaffolds, while reducing their mechanical stiffness. Furthermore, the pressure dro‎p an‎d elastic modulus values across 60%, 70%, an‎d 80% porosities varied for each scaffold, depending on factors such as surface geometry an‎d structural complexity. Among the scaffolds studied, the Truncated Cube structure exhibited the best performance in terms of both mass transfer capability an‎d stiffness. In contrast, the TPMS structure demonstrated weaker behavior due to its complex geometry an‎d the presence of continuous minimal surfaces, resulting in lower stiffness an‎d poorer mass transfer compared to other structures. For the Truncated Cube structure, the elastic modulus at 60%, 70%, an‎d 80% porosity was 283.8, 201, an‎d 84.5 MPa, respectively, while the corresponding pressure dro‎ps were 428, 246, an‎d 151 mPa indicating the highest mechanical strength an‎d best mass transfer capability among the structures. The TPMS structure, at porosities of 60%, 70%, an‎d 80%, exhibited elastic moduli of 79.1, 46.5, an‎d 19.2 MPa, an‎d pressure dro‎ps of 1524, 978, an‎d 700 mPa, respectively. The combined analysis of experimental data an‎d numerical simulations identified an optimal range of scaffold porosity an‎d geometry depending on the intended application, achieving a balance between stiffness an‎d mass transfer capability. The results indicate that the selec‎tion of scaffold type an‎d porosity percentage should be goal-oriented. The findings of this research can serve as an effective guideline for the design of bone scaffolds with optimal performance in tissue engineering applications.

مهدي كاظمي

محسن بدرسماي

عليرضا فدائي تهراني , محمد سيلاني