Micro-CT studies on 3-D bioactive glass–ceramic scaffolds for bone regeneration

Abstract

The aim of this study was the preparation and characterization of bioactive glass-ceramic scaffolds for bone tissue engineering. For this purpose, a glass belonging to the system SiO2-P2O5-CaO-MgO-Na2O-K2O (CEL2) was used. The sponge-replication method was adopted to prepare the scaffolds; specifically, a polymeric skeleton was impregnated with a slurry containing CEL2 powder, polyvinyl alcohol (PVA) as a binding agent and distilled water. The impregnated sponge was then thermally treated to remove the polymeric phase and to sinter the inorganic one. The obtained scaffolds possessed an open and interconnected porosity, analogous to cancellous bone texture, and with a mechanical strength above 2 MPa. Moreover, the scaffolds underwent partial bioresorption due to ion-leaching phenomena. This feature was investigated by X-ray computed microcomputed tomography (micro-CT). Micro-CT is a three-dimensional (3-D) radiographic imaging technique, able to achieve a spatial resolution close to 1 microm(3). The use of synchrotron radiation allows the selected photon energy to be tuned to optimize the contrast among the different phases in the investigated samples. The 3-D scaffolds were soaked in a simulated body fluid (SBF) to study the formation of hydroxyapatite microcrystals on the scaffold struts and on the internal pore walls. The 3-D scaffolds were also soaked in a buffer solution (Tris-HCl) for different times to assess the scaffold bioresorption according to the ISO standard. A gradual resorption of the pores walls was observed during the soakings both in SBF and in Tris-HCl.

Surface characterization of silicate bioceramics

“…Jones et al [84] recently showed that pore size evaluated by microCT does not always match Hg intrusion porosimetry estimates, and attributed this discrepancy to the mathematical models used to interpret Hg porosimetry data. High-quality microCT images were obtained by Renghini et al [85] using synchrotron radiation as the X-ray source. By combining microCT and computational image analysis, they were able to visualize the formation of different phases on bioactive glass-ceramic scaffolds immersed in tris and SBF (figure 10).…”

Development and Applications of Varieties of Bioactive Glass Compositions in Dental Surgery, Third Generation Tissue Engineering, Orthopaedic Surgery and as Drug Delivery System

“…As summarized in Table 2 [reproduced from (Gerhardt & Boccaccini, 2010)], most of the studies have mainly investigated the mechanical properties, in vitro and cell biological behavior of glass-ceramic scaffolds (Baino et al, 2009;Boccaccini et al, 2007;Bretcanu et al, 2008;Brown et al, 2008;Chen et al, 2007;Chen et al, 2006a;Chen et al, 2008a;Chen et al, 2006b;Deb et al, 2010;Fu et al, 2010;Fu et al, 2007;Fu et al, 2008;Ghosh et al, 2008;Haimi et al, 2009;Klein et al, 2009;Kohlhauser et al, 2009;Mahmood et al, 2001;Mantsos et al, 2009;Miguel et al, 2010;Ochoa et al, 2009;Renghini et al, 2009;Vargas et al, 2009;Vitale-Brovarone et al, 2009a;Vitale-Brovarone et al, 2010;Vitale-Brovarone et al, 2009b;Vitale-Brovarone et al, 2008;Vitale-Brovarone et al, 2004;Vitale-Brovarone et al, 2005;Vitale-Brovarone et al, 2007;Vitale Brovarone et al, 2006). Scaffolds with compressive strength (Baino et al, 2009;Fu et al, 2010) and elastic modulus values (Fu et al, 2010;Fu et al, 2008) in magnitudes far above that of cancellous bone and close to the lower limit of cortical bone have been realized.…”

“…For bioactive glass-ceramics, recent developments related to bone tissue engineering scaffolds have been used to remove the gap of load-bearing large bone defects by interplaying between architectures and components carefully designed from comprehensive levels, i.e., from the macro-, meso-, micrometer down to the nanometer scale (Deville et al, 2006), including both multifunctional bioactive glass composite structures and advanced bioactive glass-ceramic scaffolds exhibiting oriented microstructures, controlled porosity and directional mechanical properties (Baino et al, 2009;Bretcanu et al, 2008;Fu et al, 2010;Fu et al, 2008;Vitale-Brovarone et al, 2010). As summarized in Table 2 [reproduced from (Gerhardt & Boccaccini, 2010)], most of the studies have mainly investigated the mechanical properties, in vitro and cell biological behavior of glass-ceramic scaffolds (Baino et al, 2009;Boccaccini et al, 2007;Bretcanu et al, 2008;Brown et al, 2008;Chen et al, 2007;Chen et al, 2006a;Chen et al, 2008a;Chen et al, 2006b;Deb et al, 2010;Fu et al, 2010;Fu et al, 2007;Fu et al, 2008;Ghosh et al, 2008;Haimi et al, 2009;Klein et al, 2009;Kohlhauser et al, 2009;Mahmood et al, 2001;Mantsos et al, 2009;Miguel et al, 2010;Ochoa et al, 2009;Renghini et al, 2009;Vargas et al, 2009;Vitale-Brovarone et al, 2009a;Vitale-Brovarone et al, 2010;Vitale-Brovarone et al, 2009b;Vitale-Brovarone et...…”

Signals Between Cells and Matrix Mediate Bone Regeneration

“…They form a carbonated apatite layer when grafted, which is very similar to bone mineral; this will attract attachment of collagen fibres and eventually should be replaced by host tissue, mineralized matrix and cells. Other scaffolds consist of combinations of poly (lactic-coglycolic acid) (PLGA), alginate and chitosan (Huang &Miao 2007;Jose et al 2009;Mishra et al 2009;Renghini et al 2009). These polymers can also be used to carry cytokines for controlled release at the wound and/or to carry mesenchymal stem cells.…”