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MODELING THE DEGRADATION OF BIOMATERIALS WITH APPLICATIONS IN TISSUE ENGINEERING
S660
Presentation 1734 − Topic 43. Tissue engineering
MODELING THE DEGRADATION OF BIOMATERIALS WITH APPLICATIONS IN TISSUE ENGINEERING José A. Sanz-Herrera (1), Aldo R. Boccaccini (2)
1. University of Seville, Spain; 2.University of Erlangen-Nuremberg, Germany
Introduction
Results
One of the premises of Tissue Engineering indicates that the scaffold should degrade over time finally resulting in new tissue formation. In this context, numerous biomaterials with degradation capability are being investigated for scaffolds. One of the most popular biomaterials for bone tissue engineering is bioactive glass. When implanted in the human body, bioactive glasses react with the biological environment (body fluid), which dissolves the glasses through complex surface physico-chemical reactions. Glass dissolution releases a cascade of ions, which in turn react with the body fluid finally resulting in the formation of a surface hydroxyapatite (HA) layer on the scaffold surfaces. Due to the presence of this layer, the biomaterial exhibits the ability to form stable chemical bonds with the adjacent living tissue, which is termed bioactivity. In this paper, we propose a continuum approach to model degradation and bioactivity of bioactive glasses based on our previous work [Sanz-Herrera, 2011].
A unit cell of an actual bioactive glass structure (Bioglass®) is analyzed (see fig. 1). Fig. 2 shows both the degradation and mass loss in the whole unit cell of the Bioglass® scaffold versus a dimensionless time parameter. We can observe that the degradation slope changes once the HA layer is formed on the scaffold boundary (around time equal to 9). After this effect, degradation slows down as a consequence of the presence of the HA impermeable layer. Moreover, mass loss increases up to a time when it abruptly decays due to the formation of the HA layer. Once the layer is formed, it recovers the precipitate formation trend.
Materials and Methods The model is rationally developed from the analysis of the chemical reactions which take place when a bioactive glass is implanted in the human body. These equations are combined with Fickean diffusion of aqueous species within the biomaterial. The model is implemented using the Voxel-FEM method, which allows a straightforward implementation and simulation of dissolution (degradation) and precipitation (bioactivity) in the biomaterial microstructure. The reader is referred to our previous publication [Sanz-Herrera, 2011] for details of the modeling.
Conclusions A continuum approach for the modelling and simulation of bioactivity and dissolution processes in bioactive glass scaffolds has been presented. The model is useful for the analysis of this type of scaffolds for bone tissue engineering. However, it can be easily extended to other fields such as drug delivery analysis.
Acknowledgements This research was supported under grant DPI201020399-c04-02.
Figure 2: Overall degradation and mass loss in the Bioglass® specimen. Figure 1: Bioglass® scaffold microstructure (left) and unit cell model (right). Containing unit cell sphere diameter 800 m.
Journal of Biomechanics 45(S1)
References Sanz-Herrera et al, Int J Solids Struct, 48:257-268, 2011.
ESB2012: 18th Congress of the European Society of Biomechanics
Presentation 1734 − Topic 43. Tissue engineering
MODELING THE DEGRADATION OF BIOMATERIALS WITH APPLICATIONS IN TISSUE ENGINEERING José A. Sanz-Herrera (1), Aldo R. Boccaccini (2)
1. University of Seville, Spain; 2.University of Erlangen-Nuremberg, Germany
Introduction
Results
One of the premises of Tissue Engineering indicates that the scaffold should degrade over time finally resulting in new tissue formation. In this context, numerous biomaterials with degradation capability are being investigated for scaffolds. One of the most popular biomaterials for bone tissue engineering is bioactive glass. When implanted in the human body, bioactive glasses react with the biological environment (body fluid), which dissolves the glasses through complex surface physico-chemical reactions. Glass dissolution releases a cascade of ions, which in turn react with the body fluid finally resulting in the formation of a surface hydroxyapatite (HA) layer on the scaffold surfaces. Due to the presence of this layer, the biomaterial exhibits the ability to form stable chemical bonds with the adjacent living tissue, which is termed bioactivity. In this paper, we propose a continuum approach to model degradation and bioactivity of bioactive glasses based on our previous work [Sanz-Herrera, 2011].
A unit cell of an actual bioactive glass structure (Bioglass®) is analyzed (see fig. 1). Fig. 2 shows both the degradation and mass loss in the whole unit cell of the Bioglass® scaffold versus a dimensionless time parameter. We can observe that the degradation slope changes once the HA layer is formed on the scaffold boundary (around time equal to 9). After this effect, degradation slows down as a consequence of the presence of the HA impermeable layer. Moreover, mass loss increases up to a time when it abruptly decays due to the formation of the HA layer. Once the layer is formed, it recovers the precipitate formation trend.
Materials and Methods The model is rationally developed from the analysis of the chemical reactions which take place when a bioactive glass is implanted in the human body. These equations are combined with Fickean diffusion of aqueous species within the biomaterial. The model is implemented using the Voxel-FEM method, which allows a straightforward implementation and simulation of dissolution (degradation) and precipitation (bioactivity) in the biomaterial microstructure. The reader is referred to our previous publication [Sanz-Herrera, 2011] for details of the modeling.
Conclusions A continuum approach for the modelling and simulation of bioactivity and dissolution processes in bioactive glass scaffolds has been presented. The model is useful for the analysis of this type of scaffolds for bone tissue engineering. However, it can be easily extended to other fields such as drug delivery analysis.
Acknowledgements This research was supported under grant DPI201020399-c04-02.
Figure 2: Overall degradation and mass loss in the Bioglass® specimen. Figure 1: Bioglass® scaffold microstructure (left) and unit cell model (right). Containing unit cell sphere diameter 800 m.
Journal of Biomechanics 45(S1)
References Sanz-Herrera et al, Int J Solids Struct, 48:257-268, 2011.
ESB2012: 18th Congress of the European Society of Biomechanics