From Bio Waste to Bone Substitute: 3D Printing Assisted Fabrication of Scaffolds Containing High Concentrations of Eggshell Derived Hydroxyapatite

Abstract

Autografts are the gold standard for bone repair interventions due to their osteoinductive and osteoconductive properties Unfortunately, this technique entails important drawbacks such as limited availability and donor site morbidity Over the last few years, the scientific community has been developing different synthetic scaffolds as an alternative to autografts Despite the progress made in the field, there are still no ideal scaffolds with simultaneously good biocompatibility, porous three dimensional structures, bone conduction, osteoinduction, and osteogenesis Moreover, many of the proposed methods for the fabrication of scaffolds are difficult to customize to meet patient specific scaffold geometry Therefore, the present work aimed to incorporate additive manufacturing (AM or 3 D printing) in the fabrication of scaffolds containing high concentrations of eggshell derived hydroxyapatite (up to 60 wt The goal was to mimic the hard tissue composition of the human skeleton without affecting the mechanical stability of the scaffolds In order to achieve the main goal, hydroxyapatite ( was synthesized from waste eggshells via dry chemistry using ball milling In addition, porous sacrificial templates were fabricated via fused deposition modeling ( 3 D printing, which were subsequently filled with liquid/solid dispersions containing HAp and acrylonitrile butadiene styrene ( at different compositions After drying overnight, the sacrificial template was dissolved in water to finally obtain the scaffolds The fabricated materials were characterized via FTIR, microscopy, and compression test The most relevant results indicate that it was possible to use the proposed method to fabricate scaffolds with high content of hydroxyapatite (up to 60 wt of HAp) However, the high viscosity of the slurry containing 60 wt HAp created difficulties to fill properly the molds, resulting in fragile structures It was also observed that the compression modulus of the fabricated scaffolds increased with the presence of HAp into the ABS polymer matrix, obtaining the maximum value at 30 wt of HAp