Engineering 3D Printed Scaffolds with Tunable Hydroxyapatite

Abstract

Orthopedic and craniofacial surgical procedures require the reconstruction of bone defects caused by trauma, diseases, and tumor resection. Successful bone restoration entails the development and use of bone grafts with structural, functional, and biological features similar to native tissues. Herein, we developed three-dimensional (3D) printed fine-tuned hydroxyapatite (HA) biomimetic bone structures, which can be applied as grafts, by using calcium phosphate cement (CPC) bioink, which is composed of tetracalcium phosphate (TTCP), dicalcium phosphate anhydrous (DCPA), and a liquid [Polyvinyl butyral (PVB) dissolved in ethanol (EtOH)]. The ink was ejected through a high-resolution syringe nozzle (210 µm) at room temperature into three different concentrations (0.01, 0.1, and 0.5) mol/L of the aqueous sodium phosphate dibasic (Na2HPO4) bath that serves as a hardening accelerator for HA formation. Raman spectrometer, X-ray diffraction (XRD), and scanning electron microscopy (SEM) demonstrated the real-time HA formation in (0.01, 0.1, and 0.5) mol/L Na2HPO4 baths. Under those conditions, HA was formed at different amounts, which tuned the scaffolds’ mechanical properties, porosity, and osteoclast activity. Overall, this method may pave the way to engineer 3D bone scaffolds with controlled HA composition and pre-defined properties, which will enhance graft-host integration in various anatomic locations.

Tackling current production of HAp and HAp-driven biomaterials

“…171 In the context of HAp-based 3D printed scaffolds, synthetic biomaterials can be utilized to enhance the biocompatibility and osteoconductivity of the scaffold, as well as to address the processing challenges posed by the high viscosity of HAp. 23,172 Furthermore, the composition and properties of synthetic biomaterials can be precisely controlled, allowing for fine-tuning of the mechanical and biological properties of the scaffold.…”

“…22 The ability to precisely control the composition and microstructure of HAp-composite materials opens new avenues for optimizing their biological and mechanical properties for specific medical applications. 22,23 The shift towards the implementation of large-scale 3D printing technology has been a gradual process. Nevertheless, a satisfactory solution has not yet been achieved to effectively integrate existing approaches for producing uniform and scalable HAp particles into 3D matrices.…”