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Bioactive Glasses: Frontiers and Challenges.

Hench LL, Jones JR - Front Bioeng Biotechnol (2015)

Bottom Line: Bioglass formed a rapid, strong, and stable bond with host tissues.This article summarizes the frontiers of knowledge crossed during four eras of development of bioactive glasses that have led from concept of bioactivity to widespread clinical and commercial use, with emphasis on the first composition, 45S5 Bioglass(®).The four eras are (a) discovery, (b) clinical application, (c) tissue regeneration, and (d) innovation.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, Florida Institute of Technology , Melbourne, FL , USA.

ABSTRACT
Bioactive glasses were discovered in 1969 and provided for the first time an alternative to nearly inert implant materials. Bioglass formed a rapid, strong, and stable bond with host tissues. This article examines the frontiers of research crossed to achieve clinical use of bioactive glasses and glass-ceramics. In the 1980s, it was discovered that bioactive glasses could be used in particulate form to stimulate osteogenesis, which thereby led to the concept of regeneration of tissues. Later, it was discovered that the dissolution ions from the glasses behaved like growth factors, providing signals to the cells. This article summarizes the frontiers of knowledge crossed during four eras of development of bioactive glasses that have led from concept of bioactivity to widespread clinical and commercial use, with emphasis on the first composition, 45S5 Bioglass(®). The four eras are (a) discovery, (b) clinical application, (c) tissue regeneration, and (d) innovation. Questions still to be answered for the fourth era are included to stimulate innovation in the field and exploration of new frontiers that can be the basis for a general theory of bioactive stimulation of regeneration of tissues and application to numerous clinical needs.

No MeSH data available.


Related in: MedlinePlus

Sol–gel hybrids: (A) schematic of the concept of inorganic/organic hybrids with bonding between components and (B) X-ray microtomography image of sol–gel foam hybrid scaffolds. Modified with permission from Jones (2013).
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Figure 5: Sol–gel hybrids: (A) schematic of the concept of inorganic/organic hybrids with bonding between components and (B) X-ray microtomography image of sol–gel foam hybrid scaffolds. Modified with permission from Jones (2013).

Mentions: However, bioactive glass scaffolds are still brittle and therefore not suitable for all grafting applications, such as sites that are under cyclic loads. Tougher scaffolds are required that still have all the bioactive properties of Bioglass. One solution is to use composite materials (Rezwan et al., 2006); however, conventional composites of bioactive glass particles can be masked by the polymer matrix and it is difficult to match degradation rates between the polymer and the bioactive glass. An alternative is inorganic/organic hybrids made by the sol–gel process (Sanchez and In, 1992; Novak, 1993; Jones, 2013). As the gelation process occurs at room temperature, polymers can be incorporated into the sol so that the polymer chains are dispersed between the assembling nanoparticles prior to gelation. This provides molecular scale interactions between the components (Figure 5A), which gives the unique potential for control of mechanical properties and degradation rate while providing a homogeneous surface (at the micron scale) for cell attachment (Arcos and Vallet-Regi, 2010; Jones, 2013). In order for congruent degradation to occur, some covalent bonds are needed between the organic and inorganic components (Figure 5A). Examples are silica/natural polymers: e.g., silica/gelatin (Ren et al., 2002; Mahony et al., 2010, 2014), silica/poly(gamma-glutamic acid) (Poologasundarampillai et al., 2010, 2012, 2014; Valliant et al., 2013), silica/chitosan (Shirosaki et al., 2005, 2010; Connell et al., 2014), silica/polyester (Rhee et al., 2002, 2004; Pandis et al., 2015), and silica/PEG (Liu et al., 2012; Russo et al., 2013; Catauro et al., 2015; Li et al., 2015). The foaming method (Figure 5B) can be introduced to the sol–gel hybrid process (Mahony et al., 2010, 2014) or the sol to gel transition can be used to 3-D print the hybrids (Gao et al., 2013). One of the biggest challenges here is to be able to introduce calcium into the silicate network at these low processing temperatures. In sol–gel glass synthesis, using calcium salts, temperatures of 450°C must be surpassed to allow calcium to enter the silicate network, which is too high for organic components. Therefore, alternative methods for calcium incorporation are needed to impart bioactivity (Valliant et al., 2013; Poologasundarampillai et al., 2014).


Bioactive Glasses: Frontiers and Challenges.

Hench LL, Jones JR - Front Bioeng Biotechnol (2015)

Sol–gel hybrids: (A) schematic of the concept of inorganic/organic hybrids with bonding between components and (B) X-ray microtomography image of sol–gel foam hybrid scaffolds. Modified with permission from Jones (2013).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4663244&req=5

Figure 5: Sol–gel hybrids: (A) schematic of the concept of inorganic/organic hybrids with bonding between components and (B) X-ray microtomography image of sol–gel foam hybrid scaffolds. Modified with permission from Jones (2013).
Mentions: However, bioactive glass scaffolds are still brittle and therefore not suitable for all grafting applications, such as sites that are under cyclic loads. Tougher scaffolds are required that still have all the bioactive properties of Bioglass. One solution is to use composite materials (Rezwan et al., 2006); however, conventional composites of bioactive glass particles can be masked by the polymer matrix and it is difficult to match degradation rates between the polymer and the bioactive glass. An alternative is inorganic/organic hybrids made by the sol–gel process (Sanchez and In, 1992; Novak, 1993; Jones, 2013). As the gelation process occurs at room temperature, polymers can be incorporated into the sol so that the polymer chains are dispersed between the assembling nanoparticles prior to gelation. This provides molecular scale interactions between the components (Figure 5A), which gives the unique potential for control of mechanical properties and degradation rate while providing a homogeneous surface (at the micron scale) for cell attachment (Arcos and Vallet-Regi, 2010; Jones, 2013). In order for congruent degradation to occur, some covalent bonds are needed between the organic and inorganic components (Figure 5A). Examples are silica/natural polymers: e.g., silica/gelatin (Ren et al., 2002; Mahony et al., 2010, 2014), silica/poly(gamma-glutamic acid) (Poologasundarampillai et al., 2010, 2012, 2014; Valliant et al., 2013), silica/chitosan (Shirosaki et al., 2005, 2010; Connell et al., 2014), silica/polyester (Rhee et al., 2002, 2004; Pandis et al., 2015), and silica/PEG (Liu et al., 2012; Russo et al., 2013; Catauro et al., 2015; Li et al., 2015). The foaming method (Figure 5B) can be introduced to the sol–gel hybrid process (Mahony et al., 2010, 2014) or the sol to gel transition can be used to 3-D print the hybrids (Gao et al., 2013). One of the biggest challenges here is to be able to introduce calcium into the silicate network at these low processing temperatures. In sol–gel glass synthesis, using calcium salts, temperatures of 450°C must be surpassed to allow calcium to enter the silicate network, which is too high for organic components. Therefore, alternative methods for calcium incorporation are needed to impart bioactivity (Valliant et al., 2013; Poologasundarampillai et al., 2014).

Bottom Line: Bioglass formed a rapid, strong, and stable bond with host tissues.This article summarizes the frontiers of knowledge crossed during four eras of development of bioactive glasses that have led from concept of bioactivity to widespread clinical and commercial use, with emphasis on the first composition, 45S5 Bioglass(®).The four eras are (a) discovery, (b) clinical application, (c) tissue regeneration, and (d) innovation.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, Florida Institute of Technology , Melbourne, FL , USA.

ABSTRACT
Bioactive glasses were discovered in 1969 and provided for the first time an alternative to nearly inert implant materials. Bioglass formed a rapid, strong, and stable bond with host tissues. This article examines the frontiers of research crossed to achieve clinical use of bioactive glasses and glass-ceramics. In the 1980s, it was discovered that bioactive glasses could be used in particulate form to stimulate osteogenesis, which thereby led to the concept of regeneration of tissues. Later, it was discovered that the dissolution ions from the glasses behaved like growth factors, providing signals to the cells. This article summarizes the frontiers of knowledge crossed during four eras of development of bioactive glasses that have led from concept of bioactivity to widespread clinical and commercial use, with emphasis on the first composition, 45S5 Bioglass(®). The four eras are (a) discovery, (b) clinical application, (c) tissue regeneration, and (d) innovation. Questions still to be answered for the fourth era are included to stimulate innovation in the field and exploration of new frontiers that can be the basis for a general theory of bioactive stimulation of regeneration of tissues and application to numerous clinical needs.

No MeSH data available.


Related in: MedlinePlus