Fabrication of 13-93 bioactive glass scaffolds for bone tissue engineering using indirect selective laser sintering

Abstract

Bioactive glasses are promising materials for bone scaffolds due to their ability to assist in tissue regeneration. When implanted in vivo, bioactive glasses can convert into hydroxyapatite, the main mineral constituent of human bone, and form a strong bond with the surrounding tissues, thus providing an advantage over polymer scaffold materials. Bone scaffold fabrication using additive manufacturing techniques can provide control over pore interconnectivity during fabrication of the scaffold, which helps in mimicking human trabecular bone. 13-93 glass, a third-generation bioactive material designed to accelerate the body's natural ability to heal itself, was used in the research described herein to fabricate bone scaffolds using the selective laser sintering (SLS) process. 13-93 glass mixed with stearic acid (as the polymer binder) by ball milling was used as the powder feedstock for the SLS machine. The fabricated green scaffolds underwent binder burnout to remove the stearic acid binder and were then sintered at temperatures between 675 °C and 695 °C. The sintered scaffolds had pore sizes ranging from 300 to 800 µm with 50% apparent porosity and an average compressive strength of 20.4 MPa, which is excellent for non-load bearing applications and among the highest reported for an interconnected porous scaffold fabricated with bioactive glasses using the SLS process. The MTT labeling experiment and measurements of MTT formazan formation are evidence that the rough surface of SLS scaffolds provides a cell-friendly surface capable of supporting robust cell growth.

Reprint of: Review of bioactive glass: From Hench to hybrids

“…An indirect SLS method was used to produce 13-93 scaffolds with pores in the range 300-800 lm with 50% porosity and compressive strength of $20 MPa. Glass particles with a D 50 of 42 lm were used [202] with a stearic acid binder. The CAD file dictates where the laser goes and therefore which regions are sintered.…”

Quantifying the micro-architectural similarity of bioceramic scaffolds to bone

“…Additive manufacturing of bioactive glasses involves the use of layer-by-layer fabrication strategies to produce porous structures with customized external shape and pre-designed internal architecture [23]. In this regard, stereolithography [24], selective laser sintering [25] and robocasting [26] have shown a great potential (Fig. 1d), albeit additively-manufactured scaffolds usually exhibit a micro-architecture with highly-oriented pores, which is far different from the trabecular structure of cancellous bone.…”

Paper‐Derived Bioactive Glass Tape

“…The same behavior was observed for the specimens D, E, and F. The strength and elastic modulus values of the sintered specimens are similar to that of human trabecular bone. [44] The combination of microstructures and mechanical strength of the 13-93 BaG specimens studied in this work showed a high potential for the use of preceramic paper process in the fabrication of materials for bone replacement applications such as fabricating scaffolds to repair of trabecular defects. Bone tissue scaffold should possess an interconnected porous structure, with porosity >90%, pore size in the range 10-500 mm and values of mechanical strength at the range of the bone in question (e.g., for trabecular bone: failure strength of 7.6-20.7 MPa and Young's modulus of 0.05-0.5 GPa).…”

“…[43] It is known that a smaller particle size range results in a finer, sintered grain size, and improved mechanical properties. [44] Similarly, pressing of the samples prior to heat treatments gave rise for a substantial reduction of porosity both in the paper sheets preform as well as in the sintered specimens. Applying pressure to the specimens resulted in a pronounced reduction of porosity in the sintered product and an increase of strength.…”