3D Printing of Brushite-Forming Cu-Substituted β-TCP Cements for Bone Tissue Engineering

Brushite cements most features are excellent bioresorbability, osteoconductivity, and self-setting characteristics. Incorporation of relevant ions in brushite plays an essential part during the biological action course of the final cement, as well as their final mechanical properties [1]. Copper (Cu2+) is a promising trace element known to enhance osteoblasts’ activity and proliferation, and essential in new blood vessels formation [2]. 3D printing has emerged as a leading technology for producing porous structures with complex geometries, meeting the specific demands of bone tissue engineering. It offers precise control over fine architectural features such as interconnected porosity, pore size and distribution, and spatial heterogeneity—capabilities that are difficult to achieve with conventional fabrication methods. As well, the prefabrication of cements ensures complete setting before in vivo application and enabling the formation of interconnected macroporous structures. Hence, this study focused on 3D printing of brushite cements doped with Cu2+, with the goal of enhancing both degradation behavior and bone regeneration. Cements containing 0.3 mol% Cu2+ were prepared by mixing β-TCP powders with monocalcium phosphate monohydrate (MCPM) in a molar ratio of 1:0.6 [3]. Aqueous solution was prepared with 3 wt% phytic acid (inositol hexaphosphate) and 10 wt% poly(ethylene glycol), with liquid-to-powder ratio of 0.3 mL/g. The pastes were mixed and left to set for an additional 8 min before printing. The cement pastes were investigated regarding their setting reaction by XRD and isothermal calorimetry, while the hardening performance was assessed using Imeter measurements. The rheological properties were investigated to assess the printability. Printing accuracy resulting from the manufacturing process was studied by SEM and micro-CT, through the analysis of pore and filaments fidelity. The effect of both crystalline phase, ion doping, and pore structures on bone tissue regeneration were carefully studied.