| ?-tricalcium phosphate(?-TCP) has not only similar composition to bone mineral, but also good biocompatibility and bioactivity, so it has important applications in bone defects. However, the ?-TCP bioactive ceramics prepared by traditional molding process have defects that poor mechanical properties and pore canal connectivity, porosity and pore size is not controllable. These defect and deficiency impact on its clinical application. In this study, synthesized ?-TCP powder through precise regulation, and bionic built biological activity ceramic pores scaffolds materials with macropore- micropore complex multi-level structure and highly connected pore used advanced rapid prototyping technology. Solved the key problem of fabricated bioactive porous ceramic scaffolds used the rapid prototyping method by accurate design and manufacture of shape and internal porous structure. Furthermore, there are more instructive for actual implantation in vivo situation that made culture system from traditional two-dimensional to three-dimensional and study cell adhesion, migration, proliferation behavior in the interior space of porous scaffolds.Firstly, prepared raw materials with single phase, uniform particle size, small size, well-dispersed spherical ?-TCP powder, by chemical precipitation method under precise control. Then explores the heat treatment temperature effect on phase, the degree of crystallinity, grain size and boundaries. The results showed that, the precursor can not be completely converted into the crystalline phase at low temperatures, and the higher the temperature, the higher crystallinity, the greater the grain size, which lead to the adjacent particles would melt together combine two of the grain boundary together, so final choice 800 °C for the best heat treatment temperature. The particle size of ?-TCP powder synthesized using this method has a normal distribution with a median diameter of 23.258 ?m. The average density measured using double specific gravity bottles method is 3.1381 g/cm3.Developed bioceramic slurry with high solid content and good printing performance that suitable for three-dimensional fiber deposition technology of compressed gas extrusion type. Due to the maximum pressure of this extrusion systems is only 0.6 MPa, so there's a higher requirement for the slurry's fluidity and curing speed. In order to prepare of bioactive ceramic slurry used for rapid prototyping that has a high solid content, appropriate liquidity and solidification properties, and solute the slurry rheology and coagulation performance controllable and other technical issues effectively, we choose the PAA-NH4 as dispersant, added in an amount of 1.5 wt% ?-TCP powder, hydroxypropylmethyl cellulose 4000 as binder, the p H of solvent is 9, the solid content of the slurry was 40~50 vol%,Used 3D-Bioprinter system which belong to rapid prototyping technology to successfully prepared pore size and dimensions precisely controlled ?-TCP scaffolds, and investigate the effect of different sintering system and needle diameter on the physical and chemical properties of three-dimensional scaffold. Prepared different shapes and sizes 3D porous scaffolds, such as square, round, perforated square, etc. By adjusting the slurry composition makes it can be applied to rapid prototyping of 0.20 mm, 0.25 mm, 0.41 mm, 0.61 mm diameter needle. Scaffold's pore size greater than 100 ?m can be controllable. In the set of five sintering system, the phase transition did not happen, the final phase are relatively homogeneous and highly crystallinity. With the increase of sintering temperature, the porosity decreases, but continue increase of temperature would change the mass transfer mode during the sintering process, and resulting in porosity increased. The final choice of the sintering temperature is 1130 °C. Three different pore size scaffolds that include 250, 350 and 450 ?m were prepared, it's obvious that three kinds of scaffolds have distinct pore size differences which formed with a regular and orderly arrangement, and a good connectivity. The porosity of scaffolds is 39.05 ± 6.46 %, 50.14 ± 5.60 %, 48.16 ± 1.35 %, and compressive strength is 46.56 ± 13.21 MPa, 24.56 ± 3.05 MPa, 34.7 ± 2.04 MPa respectively.Studied porosity and pore size of bone tissue engineering scaffold with a high degree connectivity prepared by rapid prototyping effect on cell adhesion, proliferation, osteogenic differentiation. Cell experiments show that ?-TCP scaffolds have good biocompatibility and cell adhesion ability. Cells on the scaffold can maintain good proliferation and osteogenic differentiation, in which the 250 ?m pore size scaffold has best effect. |
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