Development of microfibers for bone regeneration based on alkali‐free bioactive glasses doped with boron oxide

Abstract

In this paper, we present a new series of alkali‐free bioactive glasses (BG) based on FastOs® composition (38.49 SiO2 – 36.07 CaO – 19.24 MgO – 5.61 P2O5 – 0.59 CaF2, expressed in mol %), which was modified by partially replacing silicon dioxide network‐former with boron trioxide network‐former, utilizing calcium oxide as a charge compensator. The main objective of this study was to obtain a new family of bioactive glasses suitable for the fabrication of glass fibers. The BGs were prepared by melt quenching technique and their structural and thermal properties were determined. Glass rods were used to obtain fibers by the classic drawing technique. The bioactivity of the fibers was subsequently assessed through immersion tests in simulated body fluid (SBF) to establish their ability to form hydroxyl carbonated (HCA) apatite onto their surfaces. Glasses with moderate substitution of SiO2 with B2O3 exhibited enhanced thermal properties, allowing to significantly suppress the crystallization trend, and favoring to draw the fibers. The structure of the studied glasses was obtained by NMR spectroscopy. The structure‐property correlations were established by their relationship to the configurational entropy. Smaller amounts of substitution resulted in larger entropy of the glasses. Moreover the SBF tests revealed an extensive formation of HCA, comparable to the parent FastOs®BG composition, which assures fast bonding to the bone. Thus, presented glass fibers may be considered as promising materials for wool‐like bone implants or as reinforcing constituent of biopolymer matrix composites.

The unexplored role of alkali and alkaline earth elements (ALAEs) on the structure, processing, and biological effects of bioactive glasses

“…Improving cytotoxicity, decreasing the tendency for crystallization, and optimizing the dissolution rate are a few good examples. [76][77][78][79] Limiting the alkali content can reduce cytotoxicity as elements like sodium rapidly increase the pH of the surrounding environment upon dissolution. Some glasses including alkali oxides have also been shown to absorb water through osmosis which limits their mechanical properties for certain applications like coatings on implants.…”

New and Efficient Bioactive Glass Compositions for Controlling Endodontic Pathogens

“…Furthermore, their different devitrification extents can be attributed to the various content and types of glass modifiers (CaO, MgO, SrO, CuO). The occurrence of liquid-liquid phase separation (LLPS) is a very common phenomenon in glasses containing different alkaline earth oxides, being ubiquitous to glass in general (e.g., Pyrex borosilicate glass) [38,39]. The presence of LLPS is unavoidable and sometimes desirable, as microscopic heterogeneities could be tuned to produce required properties [40].…”

Microcrystallization Effects in Borosilicate Bioactive Glasses: Controllable Release of Bioactive Elements and In Vitro Degradation Properties

“…The moderate release of B has been shown to facilitate tissue infiltration and cell proliferation [ 13 , 14 ], whereas rapid increases in local concentrations are counterproductive [ 15 , 16 ]. Various methods are generally adopted to regulate the initial degradation rate, including component adjustment [ 5 , 6 ], novel preparation methods [ 17 , 18 ], morphology and particle size adjustment [ 19 ], and surface premineralization [ 20 ]. However, apart from improving the initial degradation, most of these methods also have an inhibitory effect on the later release of bioactive elements, which is not conducive to mineralization.…”