Abstract
Three novel glass compositions, identified as NCL2 (SiO2-based), NCL4 (B2O3-based) and NCL7 (SiO2-based), along with apatite-wollastonite (AW) were processed to form sintered dense pellets, and subsequently evaluated for their in vitro bioactive potential, resulting physico-chemical properties and degradation rate. Microstructural analysis showed the carbonated hydroxyapatite (HCA) precipitate morphology following SBF testing to be composition-dependent. AW and the NCL7 formulation exhibited greater HCA precursor formation than the NCL2 and NCL4-derived pellets. Moreover, the NCL4 borate-based samples showed the highest biodegradation rate; with silicate-derived structures displaying the lowest weight loss after SBF immersion. The results of this study suggested that glass composition has significant influence on apatite-forming ability and also degradation rate, indicating the possibility to customise the properties of this class of materials towards the bone repair and regeneration process.
Highlights
Since the first proposed glass developed by Hench in 1969, and intended for bone tissue applications [1,2], bioactive glasses become a class of biomaterials which are still widely investigated [3].Among inorganic biomaterials, Bioglass® has received great attention for its ability to form a strong bond with soft as well as hard host tissue, resulting in what has been recognised as bioactive behaviour [4]
Sintered bioceramic pellets were successfully fabricated following the heating treatment reported in Table 2, and based on the results previously derived from HSM analysis [19]
The post sintering X-ray diffraction (XRD) pattern for NCL2 silicate-based glass revealed the presence of a crystalline phase identified as diopside (ICDD ref. code 01-073-6374)
Summary
Since the first proposed glass (currently known as Bioglass®) developed by Hench in 1969, and intended for bone tissue applications [1,2], bioactive glasses become a class of biomaterials which are still widely investigated [3].Among inorganic biomaterials, Bioglass® has received great attention for its ability to form a strong bond with soft as well as hard host tissue, resulting in what has been recognised as bioactive behaviour [4]. The concept of bioactivity was introduced by Hench at the beginning of 70's, when he described the bonding of 45S5 bioglass to bone as a process based on the formation of a carbonated hydroxyapatite (HCA) layer on the surface of the material in contact with the host tissue [2]. The development of this glass revolutionised the definition of biomaterial, moving the perspective from inert to a material that, interacting with the human body, is capable to elicit a specific biological response [5]. The SBF proposed by Kokubo mimics human blood plasma in terms of pH and ionic concentration and it is the most applied preliminary in vitro test to assess the bioactive potential of biomedical materials [10]
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