Surface Roughness and Biocompatibility of Polycaprolactone Bone Scaffolds: An Energy-Density-Guided Parameter Optimization for Selective Laser Sintering

Abstract

Three-dimensional porous polycaprolactone (PCL) bone scaffolds prepared by selective laser sintering (SLS) have demonstrated great potential in the repair of non-load-bearing bone defects. The microgeometry and surface roughness of PCL scaffolds during the SLS process may change the biocompatibility and bioactivity of the scaffolds. However, in addition to the widely concerned mechanical properties and structural accuracy of scaffolds, there is still a lack of systematic research on how SLS process parameters affect the surface roughness of PCL scaffolds and the relationship between roughness and biocompatibility of scaffolds. In this study, we use the energy density model (EDM) combined with the thermodynamic properties of PCL powder to calculate the energy density range (Ed1–Ed3) suitable for PCL sintering. Five PCL scaffolds with different laser powers and scanning speeds were prepared; their dimensional accuracy, mechanical strength, and surface properties were comprehensively evaluated, and the bioactivities were compared through the attachment and proliferation of MC3T3-E1 cells on the scaffolds. It was found that the high energy density (Ed3) reduced the shape fidelity related to pore size and porosity, and the dense and smooth surface of the scaffolds showed poor cytocompatibility, while the low energy density (Ed1) resulted in weak mechanical properties, but the rough surface caused by incomplete sintered PCL particles facilitated the cell adhesion and proliferation. Therefore, the surface roughness and related biocompatibility of PCL bone scaffolds should be considered in energy-density-guided SLS parameter optimization.

Regulation of the immune microenvironment by pioglitazone-loaded polylactic glycolic acid nanosphere composite scaffolds to promote vascularization and bone regeneration

“…Using SEM, the material surface was observed to be rough, which can encourage cell attachment, multiplication, and osteogenic differentiation. 54 , 56 Furthermore, the pore diameter of the scaffold was approximately 500 µm, which is favorable for bone formation. 57 The WCA and water swelling ratio demonstrated the strong hydrophilicity of the material, which promoted cell adhesion.…”

New Generation of Osteoinductive and Antimicrobial Polycaprolactone-Based Scaffolds in Bone Tissue Engineering: A Review

“…The key feature of the technique is the surface roughness of the printed parts. Han et al [ 87 ] carried out systematic research on how parameters of the SLS process affect the surface roughness of PCL scaffolds and the relationship between roughness and biocompatibility of constructs. Scaffolds were fabricated using various laser powers and scanning speeds.…”

A Brief Review of Current Trends in the Additive Manufacturing of Orthopedic Implants with Thermal Plasma-Sprayed Coatings to Improve the Implant Surface Biocompatibility

“…Another disadvantage of using AM for the manufacture of porous materials is the impossibility of completely melting the powders and removing all fine powders from the scaffold pores [25]. To answer these challenges, it is necessary to complicate the design of the porous implant scaffold in order to strike a balance between mechanical strength and effective bone formation ability, as well as optimize the AM parameters in order to improve the melting of powder particles [26,27]. In addition, it is important to optimize the characteristics of the pore size, porosity, and structure of the implant scaffold, taking into account the complexity of the bone structure and the numerous in vitro and in vivo tests that will be required.…”

“…It should also be noted that in a review article [24], poor surface roughness is noted as a disadvantage of SLM technology; however, there are currently no systematic studies on how SLM or SLS (Selective Laser Sintering) parameters affect the surface roughness of scaffolds or the relationship between roughness and biocompatibility of scaffolds [26]. Thus, it can be assumed that the high roughness values achieved in the SLM process (for example, the average roughness Ra = 26.6 ± 3.4 µm of 3D printed tensile specimens of the titanium alloy Ti6Al4V mentioned in [19]) may increase the biocompatibility of 3D printed titanium implants.…”