3D printed magnesium-doped ß-TCP gyroid scaffold with osteogenesis, angiogenesis, immunomodulation properties and bone regeneration capability in vivo.

Bioceramics have been used in orthopedic surgery for several years. Magnesium (Mg) is an essential element in bone tissue and plays an important role in bone metabolism. Mg-doped bioceramics has attracted the attention of researchers recently. However, the optimal doping amount of Mg in ß-TCP and the immunomodulatory property of Mg-doped ß-TCP (Mg-TCP) have not been determined yet. In this study, ß-TCP scaffolds doped with different contents of magnesium oxide (0 wt%, 1 wt%, 3 wt%, and 5 wt%) with gyroid structure were printed by digital light processing (DLP) method, and the physicochemical and biological functions were then investigated. Mg-doping improved the physicochemical properties of the ß-TCP scaffolds. In vitro experiments confirmed that the doping of Mg in ß-TCP scaffolds promoted the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) and angiogenic differentiation of endothelial progenitor cells (EPCs), where the 5Mg-TCP has the optimal properties when using the "one cell type" method. It was also found that all Mg-TCP facilitated the polarization of RAW264.7 cells to the M2 phenotype, especially the 3Mg-TCP. However, 3Mg-TCP displayed the optimal osteogenic and angiogenic potential when using a "multiple cell type" method, which referred to culturing the BMSCs or EPCs in the macrophage-conditioned medium. Finally, the in vivo experiments were conducted and the results confirmed that the 3Mg-TCP scaffolds possessed the satisfying bone defect repair capability both after 6 and 12 weeks of implantation. This study suggests that 3Mg-TCP scaffolds provide the optimal biological performance and thus have the potential for clinical translation.

Ordered Domains and Microwave Properties of Sub-micron Structured Ba(Zn1/3Ta2/3)O3 Ceramics Obtained by Spark Plasma Sintering.

The degree of Zn2+ and Ta5+ ions ordering could play an important role in the dielectric loss in Ba(Zn1/3Ta2/3)O3 (BZT) ceramics. However, the influence of the grain size of Ba(B'1/3B″2/3)O3 ceramics with nano or sub-micron grains on the ordering domains structure is still not clear. In the present paper, highly dense (~98%) BZT microwave dielectric ceramics with homogeneous sub-micron structure (~330 nm) were prepared through spark plasma sintering (SPS). High resolution transmission electron microscopy combined with X-ray diffraction (XRD)clearly showed that the B-site ordering structure of sintered BZT samples by SPS becomes the B-site long-range 1:2 ordering as annealing proceeds. In contrast, the short-range 1:2 ordering in non-annealed counterparts was also present, which was not detectable by XRD. The size of B-site ordering domains enlarged with annealing temperature. The sub-micron structure of sintered BZT ceramics by SPS remained stable at up to 1400 C; however, the size of B-site 1:2 ordering domain was more than five times larger, which led to a significant increase of the quality factor (Q·f) to 37,700 GHz from 15,000 GHz.