REATION OF ORTHOPAEDIC SCAFFOLDS FROM Mg-SUBSTITUTED HYDROXYAPATITE USING 3D PRINTING

Abstract

Synthetic hydroxyapatite [HA; Ca10(PO4)6(OH)2] is a well-researched bioceramic material for orthopaedic applications because of its chemical similarity to the inorganic constituent of bone, which accounts for nearly 70% of its mass. Nonetheless, several attempts of cationic and anionic substitutions are continuously being made in order to produce HA with increased compositional resemblance to the biological apatite, hence providing an improved therapeutic potential for bone regeneration. Magnesium (Mg) is a secondary element linked to the bone apatite, but plays a fundamental role in bone remodelling and is known to decrease bone fragility. Zinc (Zn) also demonstrates a favourable effect on the formation of bone, and its deficiency leads to a lessening in bone density & ductility. Therefore in the present study, Mg2+ & Zn2+ substituted HA was synthesized using the wet chemical precipitation route (with Mg as the major dopant) followed by a calcination treatment at various temperatures and dwell periods. The powder samples were characterized using X-Ray Diffractometry (XRD), Field-Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive X-Ray Spectroscopy (EDX), Fourier Transform Infrared Spectroscopy (FTIR), and Thermogravimetric Analysis (TGA) to ascertain the structural, morphological, compositional, molecular, and thermal properties of doped-HA. The material with the most effective synthesis parameters, namely 800ᵒC–calcined (Mg,Zn)–HA, was then selected for the creation of bone-tissue scaffolds. For any material to be 3D printed via extrusion, it should be first converted into a viscous slurry or paste (i.e. ink) and then repeatedly checked for its delicate balance of consistency and flowability. In this project, two different ink systems (non-aqueous & aqueous) were carefully formulated with the selected base material. After multiple trials and errors, thin and thick scaffolds were created using an extrusion-based 3D printer. The basic input models were designed using AutoCAD (2023) and the printer was operated via a personal computer through the DNA Studio software, from where the printing parameters were varied and controlled. The printed and sintered thin scaffolds, prepared from the non-aqueous ink system, were cut into small pieces and characterized for their morphology, elemental composition and biocompatibility.