15 Jul Additive manufacturing of polymer-ceramic composites
The Polymer Chemistry and Biomaterials group (PBM group, Ghent, Belgium) has been developing novel, photocrosslinkable poly(ε-caprolactone) (PCL), so-called Acrylate-endcapped Urethane-based PCL (AUP-PCL). AUP-PCLs are a class of biocompatible polymers that degrade thereby forming caproic acid, which can be readily resorbed. Via alteration of the crosslink density, their mechanical properties can be fine-tuned to mimic those of bone. Subsequently, in order to induce bone formation, a procedure to homogeneously incorporate hydroxyapatite (HA) into the designed AUP-PCL to function as osteogenic agent, has been established. These bioresorbable polymer-ceramic composites are promising materials in the context of bone tissue engineering as they combine proper mechanical strength and osteoinductivity.
In order to manufacture porous scaffolds of the AUP-PCL/HA composites, extrusion-based additive manufacturing (AM) has been successfully applied (Figure 1). AM is a technique by which interconnected porous scaffolds based on the individual anatomy of a patient can be obtained, leading to high-fidelity, patient-specific implants (PSI). Currently, this approach is being optimized in terms of the interconnected porous structure as this is crucial to enable bone ingrowth and vascularization of the scaffold.
Figure 1: Extrusion-based additive manufacturing of AUP-PCL containing 10 w% HA to create interconnected porous scaffolds (pore and strut diameters of 500 µm).
In collaboration with the Mechanics of Materials and Structures group (MMS group, Ghent, Belgium) design requirements such as mechanical strength and optimal pore size can be further investigated in-silico using both 3D medical imaging and finite element analysis (FEA). Computed tomography (CT) or magnetic resonance (MRI) imaging are often used to create high-resolution 3D models of the human musculoskeletal system. They can provide valuable information about the bone defect and surrounding tissues, not only in terms of the geometry of the defect but also regarding bone quality and morphology (Figure 2). This patient-specific information can be subsequently input to the finite element model to predict both the structural integrity and rate of degradation of the bioresorbable polymer-ceramic composite scaffold. We believe that the combination of AM, 3D medical imaging and FEA can provide the ultimate workflow for the development of a truly patient-specific anatomical and biomechanical scaffold design framework.
Figure 2: Patient-specific finite-element model of a bioresorbable polymer-ceramic composite scaffold for the management of a mandibular defect.
Quinten Thijssen (PBM Group, UGent, http://www.pbm.ugent.be/)
Prof. Dr. Sandra Van Vlierberghe (PBM group, UGent, http://www.pbm.ugent.be/)
Dr. Manuel Pinheiro (MMS group, UGent, http://www.composites.ugent.be/)
Prof. Dr. Wim Van Paepegem (MMS group, UGent, http://www.composites.ugent.be/)