Mechanical properties of bioactive glass (13-93) scaffolds fabricated by robotic deposition for structural bone repair

Abstract

There is a need to develop synthetic scaffolds for repairing large defects in load-bearing bones. Bioactive glasses have attractive properties as a scaffold material for bone repair, but data on their mechanical properties are limited. The objective of the present study was to comprehensively evaluate the mechanical properties of strong porous scaffolds of silicate 13-93 bioactive glass fabricated by robocasting. As-fabricated scaffolds with a grid-like microstructure (porosity = 47%; filament diameter = 330 μm; pore width = 300) were tested in compressive and flexural loading to determine their strength, elastic modulus, Weibull modulus, fatigue resistance, and fracture toughness. Scaffolds were also tested in compression after they were immersed in simulated body fluid (SBF) in vitro or implanted in a rat subcutaneous model in vivo. As fabricated, the scaffolds had a strength = 86 ± 9 MPa, elastic modulus = 13 ± 2 GPa, and a Weibull modulus = 12 when tested in compression. In flexural loading, the strength, elastic modulus, and Weibull modulus were 11 ± 3 MPa, 13 ± 2 GPa, and 6, respectively. In compression, the as-fabricated scaffolds had a mean fatigue life of ~106 cycles when tested in air at room temperature or in phosphate-buffered saline at 37 °C under cyclic stresses of 1–10 MPa or 2–20 MPa. The compressive strength of the scaffolds decreased markedly during the first 2 weeks of immersion in SBF or implantation in vivo, but more slowly thereafter. The brittle mechanical response of the scaffolds in vitro changed to an elasto-plastic response after implantation for longer than 2–4 weeks in vivo. In addition to providing critically needed data for designing bioactive glass scaffolds, the results are promising for the application of these strong porous scaffolds in loaded bone repair.

Effects of magnesium silicate on the mechanical properties, biocompatibility, bioactivity, degradability, and osteogenesis of poly(butylene succinate)-based composite scaffolds for bone repair

“…The compressive strengths were determined from the peak of the stress-strain curve. The porosity of the scaffolds was determined by using the Archimedes method at room temperature, 17 which was calculated as:…”

Ductile silica/methacrylate hybrids for bone regeneration

“…5 A second mode of action is its dissolution products (in particular silica), which enhance osteoblast activities, whilst promoting extra-cellular matrix (ECM) production and cells differentiation. [6][7][8] 3D scaffolds have been produced from bioactive glasses, with interconnected pore networks in the form of foams 9,10 or 3-D printed structures 11 , which can take load in compression, up to 150 MPa when 3D printed. 12 However, glasses are brittle and are unable to take cyclic loads.…”

Preparation and Characterization of Macroporous Bioactive Glass Ceramic made via Sol-Gel Route and Powder Sintering Method

“…We have found that, there were very limited studies on sintering of glass particles in preparation of macroporous scaffolds due to the fact that sintering is known to reduce the glass initial bioactivity (Izadi et al 2014;Liu et al 2013b;Sabree et al 2015). However, recent study also showed the sintered glass especially the one that contained high percentage of network modifier such as calcium and sodium has maintained or even increased their bioactivity property (Esfehani et al 2013;Jones et al 2010;Kamalian et al 2012).…”

“…Numerous studies have been conducted in preparing macroporous ceramic scaffold which involved techniques such as polymer burnout, foam synthesis and template replication method Jones et al 2006;Liu et al 2013a;Stábile et al 2015;Wu et al 2011). These techniques particularly produced highly interconnected porous structures, however lack in mechanical strength (Izadi et al 2014;Jones et al 2006;Liu et al 2013b). …”