Porous Glass-ceramic Scaffolds Research Articles

Micro-CT based finite element models for elastic properties of glass–ceramic scaffolds

In this study, the mechanical properties of porous glass–ceramic scaffolds are investigated by means of three-dimensional finite element models based on micro-computed tomography (micro-CT) scan data. In particular, the quantitative relationship between the morpho-architectural features of the obtained scaffolds, such as macroscopic porosity and strut thickness, and elastic properties, is sought.The macroscopic elastic properties of the scaffolds have been obtained through numerical homogenization approaches using the mechanical characteristics of the solid walls of the scaffolds (assessed through nanoindentation) as input parameters for the numerical simulations. Anisotropic mechanical properties of the produced scaffolds have also been investigated by defining a suitable anisotropy index. A comparison with morphological data obtained through the micro-CT scans is also presented. The proposed study shows that the produced glass–ceramic scaffolds exhibited a macroscopic porosity ranging between 29% and 97% which corresponds to an average stiffness ranging between 42.4GPa and 36MPa. A quantitative estimation of the isotropy of the macroscopic elastic properties has been performed showing that the samples with higher solid fractions were those closest to an isotropic material.

Microstructural characterization and in vitro bioactivity of porous glass-ceramic scaffolds for bone regeneration by synchrotron radiation X-ray microtomography

Abstract One of the key purposes of bone tissue engineering is the development of new biomaterials that can stimulate the body's own regenerative mechanism for patient's anatomical and functional recovery. Bioactive glasses, due to their versatile properties, are excellent candidates to fabricate porous 3-D architectures for bone replacement. In this work, morphological and structural investigations are carried out on Bioglass ® - and CEL2-derived scaffolds produced by sponge replication (CEL2 is an experimental glass developed at Politecnico di Torino). Synchrotron radiation X-ray microtomography is used to study the samples 3-D architecture, pores size, shape, distribution and interconnectivity, as well as the growth kinetics on scaffolds struts of a newly formed apatitic phase during in vitro treatment in simulated body fluid, in order to describe from a quantitative viewpoint the bioactive potential of the analyzed biomaterials. An accurate comparison between architectural features and bioactive behaviour of Bioglass ® - and CEL2-derived scaffolds is presented and discussed.

Porous β-NaCaPO 4 containing borate glass-ceramic scaffolds

A novel β-NaCaPO 4 containing borate glass-ceramic is prepared. Two porous glass-ceramic scaffolds are prepared by binding particles with the size of 200–300 μm by 5 wt.% sodium silicate solution and 2 wt.% chitosan solutions, respectively. The reaction of the scaffolds in the SBF solution is characterized by weight loss analysis, XRD, FTIR, and SEM. The same is done to the 45S5 glass scaffolds as comparison. XRD and FTIR indicate that the carbonate hydroxyapatite has formed more rapidly on the borate glass-ceramic scaffolds. The carbonated hydroxyapatite depositing on chitosan binding scaffolds has lower crystallization degree than that on sodium silicate binding scaffolds and is similar to that of the human bone, which makes the chitosan binding scaffolds a good potential prospect in the field of tissue engineering.

Borophosphate glass-ceramic scaffolds by a sodium silicate bonding process

A borophosphate glass with the mol% composition 25Na 2O-25CaO-5P 2O 3-45B 2O 5 was melted. The crystalline phase rheanite crystallized spontaneously during cooling the sample. Porous glass-ceramic scaffolds were prepared by bonding glass particles with size distributions in the range of approximately 100–500 μm by 0.1 M Na 2SiO 3 solutions. The scaffolds porosities were 40 ~ 60% and their compressive strengths were 0.1 ~ 0.4 MPa. The conversion of the binding scaffolds to hydroxyapatite (HA) was investigated by measuring the weight loss after soaking the sample in a solution of 0.25 M K 2HPO 4 with a pH value of 9.0 at 37 °C as a function of time. Hydroxyapatite (HA) was observed by XRD and SEM after soaking for 7 days. Cell attachment, spreading and proliferation on both unconverted scaffolds and on scaffolds coated with HA were determined by MTT [3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide] assay method using Murine osteoblastic-like MC3T3-E1 cells. The scaffolds are biocompatible and their biocompatibility is enhanced after the formation of a HA layer.

Preparation and biocompatibility evaluation of apatite/wollastonite-derived porous bioactive glass ceramic scaffolds

An apatite/wollastonite-derived (A/W) porous glass ceramic scaffold with highly interconnected pores was successfully fabricated by adding a plastic porosifier. The morphology, porosity and mechanical strength were characterized. The results showed that the glass ceramic scaffold with controllable pore size and porosity displayed open macropores. In addition, good in vitro bioactivity was found for the scaffold obtained by soaking it in simulated body fluid. Mesenchymal stem cells (MSCs) were cultured, expanded and seeded on the scaffold, and the adhesion and proliferation of MSCs were determined using MTT assay and environmental scanning electron microscopy (ESEM). The results revealed that the scaffold was biocompatible and had no negative effects on the MSCs in vitro. The in vivo biocompatibility and osteogenicity were investigated by implanting both the pure scaffold and the MSC/scaffold construct in rabbit mandibles and studying histologically. The results showed that the glass ceramic scaffold exhibited good biocompatibility and osteoconductivity. Moreover, the introduction of MSCs into the scaffold observably improved the efficiency of new bone formation, especially at the initial stage after implantation. However, the glass ceramic scaffold showed the same good biocompatibility and osteogenicity as the hybrid one at the later stage. These results indicate that porous bioactive scaffolds based on the original apatite–wollastonite glass ceramic fulfil the basic requirements of a bone tissue engineering scaffold.

Preparation of porous 45S5 Bioglass®-derived glass–ceramic scaffolds by using rice husk as a porogen additive

Bioactive glass is currently regarded as the most biocompatible material in the bone regeneration field because of its bioactivity, osteoconductivity and even osteoinductivity. In the present work porous glass-ceramic scaffolds, which were prepared from the 45S5 Bioglass by foaming with rice husks and sintering at 1050 degrees C for 1 h, have been developed. The produced scaffolds were characterized for their morphology, properties and bioactivity. Micrographs taken using a scanning electron microscope (SEM) were used for analysis of macropores, mesopores and micropores, respectively. The bioactivity of the porous glass-ceramic scaffolds was investigated using simulated body fluid (SBF) and characterized by SEM, energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). A great potential scaffold that provides sufficient mechanical support temporarily while maintaining bioactivity, and that can biodegrade at later stages is achievable with the developed 45S5 Bioglass-derived scaffolds.

Fabrication of bi-layers porous glass-ceramic scaffolds using the replication methods

Fabrication of bi-layers porous glass-ceramic scaffolds using the replication methods

Characterisation of highly porous glass ceramic scaffolds

Abstract Highly porous glass ceramic scaffolds are compared by X-ray refraction topography and optical microscopic image analysis. The micro pore structures of the spongosia-like material are characterised in order to optimise sample preparation and sinter process parameters. In contrast to the specific internal surfaces determined by optical microscopy, significantly higher values are found by X-ray refraction. This discrepancy is explained by additional scanning electron microscopy detecting various types of sub-micron interfaces within the scaffold super-structure. The study demonstrates the necessity of both methods in order to gain more reliable information. More generally, this is also recommended for characterising other porous materials of very different structural dimensions.