Bioactive ceramics have received great attention in the past decades owing to their success in stimulating cell proliferation, differentiation and bone tissue regeneration. They can react and form chemical bonds with cells and tissues in human body. This paper provides a comprehensive review of the application of bioactive ceramics for bone repair and regeneration. The review systematically summarizes the types and characters of bioactive ceramics, the fabrication methods for nanostructure and hierarchically porous structure, typical toughness methods for ceramic scaffold and corresponding mechanisms such as fiber toughness, whisker toughness and particle toughness. Moreover, greater insights into the mechanisms of interaction between ceramics and cells are provided, as well as the development of ceramic-based composite materials. The development and challenges of bioactive ceramics are also discussed from the perspective of bone repair and regeneration.
A tetragonal polyvinyl alcohol (PVA) scaffold with 3D orthogonal periodic porous architecture was fabricated via selective laser sintering (SLS) technology. The scaffold was fabricated under the laser power of 8 W, scan speed of 600 mm min(-1), laser spot diameter of 0.8 mm and layer thickness of 0.15 mm. The microstructure analysis showed that the degree of crystallization decreased while the PVA powder melts gradually and fuses together completely with laser power increasing. Thermal decomposition would occur if the laser power was further higher (16 W or higher in the case). The porous architecture was controllable and totally interconnected. The porosity of the fabricated scaffolds was measured to be 67.9 ± 2.7% which satisfies the requirement of micro-pores of the bone scaffolds. Its bioactivity and biocompatibility were also evaluated in vitro as tissue engineering (TE) scaffolds. In vitro adhesion assay showed that the amount of pores increased while the scaffold remains stable and intact after immersion in simulated body fluid for seven days. Moreover, the number of MG-63 cells and the bridge between cells increased with increasing time in cell culture. The present work demonstrates that PVA scaffolds with well-defined porous architectures via SLS technology were designed and fabricated for bone TE.
Calcium silicate ( CaSiO 3) is a promising material due to its favorable biological properties. However, it was difficult to fabricate ceramic scaffolds with interconnected porous structure via conventional technology. In present study, CaSiO 3 scaffolds with totally interconnected pores were fabricated via selective laser sintering (SLS). The microstructure, mechanical and biological properties were examined. The results revealed that the powder gradually fused together with the reduction of voids and the elimination of particle boundary as the laser power increased in the range of 3–15 W with scanning electron microscope. Meanwhile the low-temperature phase (β- CaSiO 3) transformed into high-temperature phase (α- CaSiO 3) gradually, which decreased the mechanical properties of the obtained scaffolds. Besides, the compressive strength increased from 12.9 ± 2.34 MPa to 18.19 ± 1.24 MPa (the laser power is 12 w) and then decreased gradually with increasing laser power. In vitro biological properties of CaSiO 3 scaffolds sintered under optimal conditions indicated that the distribution of apatite mineralization became uniform as the amount of them increased after being immersed in simulated body fluids. In the meantime, the thin cytoplasmic extensions of MG-63 cells increased until formed a dense cell layer after 1–5 days of cell culture. The results suggested that the CaSiO 3 scaffold fabricated via SLS has potential application for bone tissue engineering.
Biodegradable polymer/bioceramic composite scaffolds can overcome the limitations of polymer scaffolds such as poor compressive strength and bioactivity. In this study, poly(vinyl alcohol)/calcium silicate (CaSiO3) composite scaffolds with fully interconnected porous structures and customized shapes were successfully fabricated via selective laser sintering. The microstructure, porosity, and mechanical properties of the scaffolds were characterized. Based on the results, CaSiO3 particles were well dispersed and embedded in the poly(vinyl alcohol) matrix after sintering. The compressive strength increased with increasing the content of CaSiO3 up to 15 wt%, and then decreased with further increasing CaSiO3 content to 20 wt%. Our study also revealed that the scaffolds could not be fabricated successfully as fewer poly(vinyl alcohol) particles fused together when CaSiO3 was higher than 20 wt%. Based on the in vitro data, the poly(vinyl alcohol)/CaSiO3 composite scaffolds possess good bioactivity and cytocompatibility.
Complex three-dimensional (3D) porous scaffolds with macro-pore size of 400À800 m based on polyvinyl alcohol (PVA) powder were successfully developed by selective laser sintering (SLS) technology. The PVA scaffolds had customizable shape, controlled and totally interconnected porous structure, and high porosity. The microstructure and mechanical property were performed for their suitability for tissue engineering (TE). The results showed that PVA did not decompose while the degree of crystallization decreased in a given sintering condition. Moreover, there were micro-pores with sizes of 20À100 m in the scaffold. The actual porosity of sintered scaffolds could be up to 82.35%, which was higher than the value of the designed models. An in vitro biocompatibility test showed MG-63 cells could well spread on the scaffold surface. The presented work demonstrates the favorable potential of PVA powder as TE scaffolds fabricated via SLS.
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