Effects of biopolymer functionalization and nanohydroxyapatite heat treatment on the tensile and thermomechanical properties of Bone-Inspired 3D printable nanocomposite biomaterials

Abstract

Bone-inspired biopolymer nanocomposite grafts are an alternative to conventional bone substitutes if designed to offer a structure with adequate mechanical properties and biocompatibility. In this study, a set of novel 3D printable bone-inspired nanocomposite biomaterials was developed to investigate the effects of additional cross-linking of the biopolymer matrix and heat treatment of nHA particles on the tensile and thermo-mechanical properties of these nanocomposites used in extrusion-based 3D printing. We observed that additional functionalization of acrylated epoxidized soybean oil (AESO), as the main component of the biopolymer matrix, with additional methacrylate groups (mAESO), increased the strength and elastic modulus of extruded nanocomposites by more than three times, as well as doubled the glass transition temperature due to an increased degree of crosslinking in the functionalized matrices. The mAESO-based nanocomposite filaments demonstrated a strength safety factor of 1.5 against the minimum required standard mechanical properties for bone cement according to ISO standard5833. While heat treatment of nHA reduced the frequency of larger agglomerations, no significant difference in mechanical properties was observed. These novel 3D printable nanocomposite biomaterials with their improved strength, modulus and thermo-mechanical properties could be suitable candidates for fabricating complex ‘by design’ 3D printed grafts and scaffolds for bone reconstruction.