Study of the mechanical stability and bioactivity of Bioglass ^® based glass-ceramic scaffolds produced via powder metallurgy-inspired technology

Abstract

Large bone defects are challenging to heal, and often require an osteoconductive and stable support to help the repair of damaged tissue. Bioglass-based scaffolds are particularly promising for this purpose due to their ability to stimulate bone regeneration. However, processing technologies adopted so far do not allow for the synthesis of scaffolds with suitable mechanical properties. Also, conventional sintering processes result in glass de-vitrification, which generates concerns about bioactivity. In this work, we studied the bioactivity and the mechanical properties of Bioglass® based scaffolds, produced via a powder technology inspired process. The scaffolds showed compressive strengths in the range of 5–40 MPa, i.e. in the upper range of values reported so far for these materials, had tunable porosity, in the range between 55 and 77%, and pore sizes that are optimal for bone tissue regeneration (100–500 μm). We immersed the scaffolds in simulated body fluid (SBF) for 28 d and analyzed the evolution of the scaffold mechanical properties and microstructure. Even if, after sintering, partial de-vitrification occurred, immersion in SBF caused ion release and the formation of a Ca-P coating within 2 d, which reached a thickness of 10–15 μm after 28 d. This coating contained both hydroxyapatite and an amorphous background, indicating microstructural amorphization of the base material. Scaffolds retained a good compressive strength and structural integrity also after 28 d of immersion (6 MPa compressive strength). The decrease in mechanical properties was mainly related to the increase in porosity, caused by its dissolution, rather than to the amorphization process and the formation of a Ca-P coating. These results suggest that Bioglass® based scaffolds produced via powder metallurgy-inspired technique are excellent candidates for bone regeneration applications.

A comprehensive study on compositional and structural changes in 45S5 bioglass products exposed to simulated body fluid

“…Before examining the results obtained in the present work relatively to the behavior displayed by these three groups of samples during in vitro tests, some preliminary considerations are worth to be made. In particular, it should be mentioned that the physiological media used in various studies reported in the literature were periodically refreshed . Such choice was aimed to maintain the ions concentration more stable during the test.…”

Current perspectives on biological approaches for osteoarthritis

“…It is a major challenge using autologous decellularized bone, which promotes donor site morbidity, while there is an increased risk of disease transmission and immune response using allogenic decellularized bone. Several promising synthetic options also exist, such as glass–ceramic, hydroxyapatite, fibronectin, alginate, and biphasic calcium phosphate, which reduce the risk of an immunological response but may lack material properties and factors native to human bone, which would reduce their efficacy as scaffolds. There is continued effort to design an implantable natural or synthetic scaffold with stem cells or bioactive factors that modulates a subsequent immunological response that consists of native‐like biological materials to regenerate bony defects …”

Bioactive behavior of mesoporous silica particle (MCM‐41) coated bioactive glass‐based scaffolds

“…[4][5][6] The 45S5 BG composition (in mol% 46.1% SiO 2 , 24.4% Na 2 O, 26.9% CaO and 2.6% P 2 O 5 ) 4 has been used for several clinical purposes, eg dental and orthopedic applications, and as monolith or in particulates form in non-load-bearing sites. The main difficulty is to fabricate highly porous scaffolds with mechanical strength comparable to that of natural cancellous bone (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12). The main difficulty is to fabricate highly porous scaffolds with mechanical strength comparable to that of natural cancellous bone (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12).…”

“…The main difficulty is to fabricate highly porous scaffolds with mechanical strength comparable to that of natural cancellous bone (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12). [9][10][11] In this way, it was possible to obtain superior mechanical properties without affecting the bioactivity of the starting material and without compromising the possible cell ingrowth and neovascularization of the three-dimensional structure. [9][10][11] In this way, it was possible to obtain superior mechanical properties without affecting the bioactivity of the starting material and without compromising the possible cell ingrowth and neovascularization of the three-dimensional structure.…”

“…7,8 In the past years, an alternative approach has been considered, namely the development of BG-based scaffolds with increased mechanical properties, which is achieved by the reduction of the total porosity (68%) without affecting pore interconnectivity (>99%). 11,12 There is increasing interest in enhancing the functionalities of such scaffolds by coating them with ordered mesoporous materials, 13,14 eg mesoporous silica (MCM-41) particles, in order to introduce drug delivery capability and controlled nanoscale roughness. 11,12 There is increasing interest in enhancing the functionalities of such scaffolds by coating them with ordered mesoporous materials, 13,14 eg mesoporous silica (MCM-41) particles, in order to introduce drug delivery capability and controlled nanoscale roughness.…”