论文部分内容阅读
3D printing of calcium phosphate (CaP) scaffolds has great promise to fabricate custom bone substitutes. The aim of this study is to explore one kind of CaP paste with tunable injectability and setting ability for lower temperature 3D printing by mechanical activation CaP powders and adding gelatin. Starting CaP powder was composed of α-tricalcium phosphate (α-TCP), hydroxyapatite (HA), calcium phosphate dehydrate (DCPD) and calcium carbonate (CaCO3). Gel, hydrophilic and viscous polymer, was added to phosphate buffer solution (PBS) as the liquid phase and simultaneously added to the synthesis of DCPD. X-ray diffraction (XRD), Particle size analyzer, Automated surface area and Pore size analyzer were used to characterize as-received CaP powders. Injectability and setting time of MCaP paste were measured for 3D printing of CaP/Gel scaffold. The average particle size and density of mechanical activation CaP (MCaP) powders decreased while the specific surface area of MCaP increased compared to those of the control CaP powders without mechanical activation. As a result, it led to the higher liquid-to-solid ratio of MCaP paste compared to that of the control CaP paste. XRD indicated that the grain sizes and crystallinities of MCaP powders decreased compared to those of the control CaP powders. The final setting time of MCaP-Gel paste (12±0.8 min) decreased obviously compared to that of MCaP (16±0.5 min) paste and CaP paste (25±0.3 min). The continuous 3D printing and stacking of CaP paste layer need the quick setting but the extrusion of CaP paste need the slow setting. Therefore, the suitable setting time was adjusted to meet the requirement of 3D printing furthermore. The injectability of MCaP-Gel (86±1.0 %) was lower than that of MCaP (93±0.6 %), while significantly higher than that of CaP paste (45±1.0 %). The higher injectability of MCaP might be due to its higher liquid-to-solid ratio, smaller particle size and the adding of Gel. Moreover, Gel solution was beneficial to overcome the solid-liquid separation of paste in the extrusion of 3D printing and promoted the setting reaction of MCaP. Finally, the present tunable MCaP-Gel paste had been carried out 3D printing. It is feasible to carry out the lower temperature 3D printing for CaP based custom scaffold by using MCaP-gel paste with the tunable injectability and setting ability. This lower temperature 3D printing CaP is available for drug-loaded. In addition, the low temperature CaP is expected to show both excellent osteoconductivity and osteclastic resorbability in vivo.