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To improve the biological performance of hydroxyapatite scaffolds in bone tissue engineering, graphite was used as porogen to create additional micro/nanoporosity to macroporosity, resulting in hierarchical porosity. For maximum imitation of natural bone structures, scaffolds with different porosity features were fabricated using micron/nano-sized graphite. The sintering profile of graphite treated scaffolds was optimised to reduce the influence of shrinkage. To confirm the porosity features, the micro/nanostructures of scaffolds were characterised by scanning electron microscopy and Brunauer-Emmett-Teller method. Considering that hydroxyapatite is resistant to biodegradation in vivo, the degradation rate of scaffolds in modified simulated body fluid was examined. Furthermore, biological evaluations based on myoblasts were carried out to investigate the influence of porosity features on the essential performance such as adhesion, proliferation and differentiation. The results indicate that the scaffolds with dominant microporosity and little nanoporosity formed inside had high potential for clinical applications due to improved performance in bioactivity. [ABSTRACT FROM AUTHOR]

Zirconia-alumina composite ceramics are the preferred materials for high temperature and thermal shock applications because of their excellent mechanical properties. In this paper, La 2 O 3 doped zirconia-alumina composite ceramics were prepared by using fused zirconia corundum and ZrO 2 as starting materials. The effects of La 2 O 3 on the phase composition, microstructure and properties of the composite ceramics were investigated by XRD and SEM. The results show that La 2 O 3 can reduce the sintering temperature and improve the bending strength of the samples. The bending strength and fracture toughness of the composite ceramics with 1.5 wt% La 2 O 3 sintered at 1480 °C are 299.17 MPa and 5.61 MPa m1/2, respectively. The strength loss rate of the sample after 30 thermal shocks (room temperature ∼ 1000 °C) is 2.67%, SEM shows that the grain sizes of alumina and zirconia in the sintered sample were about 5 μm and 2 μm, respectively. After 30 thermal shocks, the phase composition and microstructure of the sample have no significant change, indicating good thermal shock resistance of the composite ceramics. The excellent thermal shock resistance ensures porous medium combustion materials has a long service life. [ABSTRACT FROM AUTHOR]

Extrusion freeforming is a facile approach to produce complex 3D structures with controlled architecture and porosity. In this work, a new slurry system, mainly containing hydroxyapatite (HA) and sodium alginate (SA), has been used to fabricate porous hydroxyapatite scaffolds. After cross-linking in 5% calcium chloride (CaCl 2 ) solution for 24 h, HA–SA composite scaffolds were sintered at 1000–1300 °C for 2 h. The properties of HA–SA composite scaffolds before and after sintering have been investigated. The new slurry system has greatly improved the quality of porous hydroxyapatite scaffolds. [ABSTRACT FROM AUTHOR]

Digital light processing (DLP)-based ceramic stereolithography has attracted significant attentions due to the high printing speed and high dimensional accuracy of DLP printers. However, undesired dropping of unfinished ceramic parts during printing, owing to inadequate adhesion between the first cured layer and the substrate of the building platform, still remains a challenge. In this study, the relationship between the adhesion properties of ultraviolet (UV)-curable alumina (α-Al 2 O 3) suspensions and the functionalities and structures of UV-curable acrylate monomers was investigated. With an increase in the proportions of monofunctional monomers, the adhesion abilities of UV-curable alumina suspensions enhanced because of reduced volume shrinkage, however, inferior curing performances were observed due to a decrease in the double bond densities. Furthermore, the large-volume branched chain structures in monofunctional monomers and ethyoxyl groups in polyfunctional monomers effectively decreased the volume contraction, improving the adhesion performances of UV-curable alumina suspensions and facilitating the conversion of double bonds to provide excellent curing properties, further guaranteeing strong adhesion of these suspensions to the substrate. [ABSTRACT FROM AUTHOR]

Silver nanoparticle (Ag-np) is a new kind of antibacterial agent which is widely used in medical supplies. In this study, a simple approach is described to obtain Ag-doped HA scaffolds. Hydroxyapatite (HA) bone scaffolds with controllable pore size were fabricated by a micro-syringe extrusion system. Sintered HA scaffolds were then immersed in silver reaction hydrosol in order to get Ag-doped HA scaffolds. SEM and EDS shows a uniform distribution of silver nanoparticles on the surface of HA scaffolds. Such Ag-np doped HA scaffolds, displaying a good antibacterial activity against Escherichia coli ( E. coli ), are likely to prevent bone implant associated bacterial infections. [ABSTRACT FROM AUTHOR]