Bioactive Ceramic Scaffolds for Bone Tissue Engineering by Powder Bed Selective Laser Processing: A Review

The implementation of a powder bed selective laser processing (PBSLP) technique for bioactive ceramics, including selective laser sintering and melting (SLM/SLS), a laser powder bed fusion (L-PBF) approach is far more challenging when compared to its metallic and polymeric counterparts for the fabrication of biomedical materials. Direct PBSLP can offer binder-free fabrication of bioactive scaffolds without involving postprocessing techniques. This review explicitly focuses on the PBSLP technique for bioactive ceramics and encompasses a detailed overview of the PBSLP process and the general requirements and properties of the bioactive scaffolds for bone tissue growth. The bioactive ceramics enclosing calcium phosphate (CaP) and calcium silicates (CS) and their respective composite scaffolds processed through PBSLP are also extensively discussed. This review paper also categorizes the bone regeneration strategies of the bioactive scaffolds processed through PBSLP with the various modes of functionalization through the incorporation of drugs, stem cells, and growth factors to ameliorate critical-sized bone defects based on the fracture site length for personalized medicine.

Sol-Gel Synthesis of Soda Lime Silica-Based Bioceramics Using Waste as Renewable Sources

The purpose of the work is to prepare and assess soda lime silica-based (SiO2-CaO-Na2O) bioactive ceramics using waste as renewable sources. Thus we produced a SiO2-CaO-Na2O-based bioactive ceramic by sol-gel process using rice husk and eggshells as sources of silica and calcium oxide, respectively. The precursors such as calcinated eggshell powder, rice husk ash (RHA) and sodium hydroxide (NaOH) were processed by the sol-gel method, resultant in SiO2-CaO-Na2O-based bioactive ceramics. The gel derived sintered sample showed combeite high (Na6Ca3Si6O18) as a major crystalline phase. Subsequently, the sintered specimens were analyzed from the physical and structural point of view, and in terms of apatite mineralization rate in simulated environments and cytocompatibility in relative to human osteoblast-like cells. The studies showed that the produced crystalline SiO2-CaO-Na2O-based ceramics showed an average porosity of 45%. In vitro evaluation of the biological properties revealed that the prepared ceramics possesses the mineralization of carbonated hydroxyapatite (CHA) in a simulated environment with good cytocompatibility and controlled degradation rate. Therefore, the results obtained suggest that the prepared SiO2-CaO-Na2O-based bioactive ceramics using waste as renewable sources might be a low cost ceramics for applications in biomedical field.

Mg-Based Composites for Biomedical Applications

Magnesium (Mg) is a promising material for producing temporary orthopedic implants, since it is a biodegradable and biocompatible metal which density is very similar to that of the bones. Another benefit is the small strength mismatch when compared to other biocompatible metals, what alleviates stress-shielding effects between bone and the implant. To take advantage of the best materials properties, it is possible to combine magnesium with bioactive ceramics and tailor composites for medical applications with improved biocompatibility, controllable degradation rates and the necessary mechanical properties. To properly insert bioactive reinforcement into the metallic matrix, the fabrication of these composites usually involves at least one high temperature step, as casting or sintering. Yet, recent papers report the development of Mg-based composites at room temperature using severe plastic deformation. This chapter goes through the available data over the development of Mg-composites reinforced with bioactive ceramics, presenting the latest findings on the topic. This overview aims to identify the major influence of the processing route on matrix refinement and reinforcement dispersion, which are critical parameters to determine mechanical and corrosion properties of biodegradable Mg-based composites.