M.Sc. Marcela Arango-Ospina | University of Erlangen-Nuremberg | Germany
Fangtong Xie | Technische Universität Darmstadt | Germany
Isabel Gonzalo-Juan | Technische Universität Darmstadt | Germany
Dr. rer. nat. Emanuel Ionescu | Technische Universität Darmstadt | Germany
Prof. Ralf Riedel | Technische Universität Darmstadt | Germany
Prof. Aldo R Boccaccini | University of Erlangen-Nuremberg | Germany
Bioactive glasses are known to be promising biomaterials for applications in bone regeneration due to the interactions with body fluids during their dissolution process. The incorporation of therapeutic ions in the glass composition is meant to enhance osteogenic and angiogenic properties of the material, boron and strontium are considered therapeutic ions known for promoting bone cell adhesion and stimulating bone formation. Bioactive glasses based on silicon oxycarbide and produced from a polymeric single-source precursor, are of interest due to their outstanding devitrification resistance and ability to retain their amorphous structure at high temperatures. In this study, silicon oxycarbide-based bioactive glasses were produced via thermal conversion (pyrolysis) and doped with B and Sr (SiBCaSrOC). In vitro activity was assessed by incubating the samples in simulated body fluid (SBF) over a period of two weeks and characterized using Scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Additionally, cell proliferation studies using mouse embryonic fibroblasts (MEFs) in an indirect experiment set-up were carried out. Furthermore, the expression and secretion of vascular endothelial growth factor (VEGF) from the cultured cells was measured.
 Hoppe A., et al., A review of the biological response to ionic dissolution products from bioactive glasses and glass-ceramics, Biomaterials 2011, 32(11) 2757-2774.
 Gonzalo-Juan, I., et al., Synthesis and In Vitro Activity Assessment of Novel Silicon Oxycarbide-Based Bioactive Glasses, Materials 2016, 9(12), 959.
Effects of crystallisation on in vitro bioactivity in fluoride-containing bioactive glasses
Gloria Kirste | Otto-Schott-Institut für Materialforschung, Friedrich-Schiller-Universität Jena | Germany
Assoc. Prof. Jonathan Massera | Faculty of Biomedical Sciences and Engineering, Tampere University of Technology | Finland
PhD Natalia Karpukhina | Barts and The London School of Medicine and Dentistry, Queen Mary University of London | United Kingdom
Prof Hill Robert | Barts and The London School of Medicine and Dentistry, Queen Mary University of London | United Kingdom
Prof. Delia S. Brauer | Otto-Schott-Institut für Materialforschung, Friedrich-Schiller-Universität Jena | Germany
Bioactive glass powders or granules are used clinically as bone scaffolds. While their use as porous 3D samples is preferred, their preparation is limited by their tendency to crystallise during sintering, which has been reported to negatively affect ion release and in vitro apatite mineralisation. Therefore, this study investigated the effect of crystallisation on in vitro bioactivity in a SiO2-P2O5-CaO-CaF2 system. Phosphate was added together with CaO to maintain the silicate polymerisation, while CaF2 was added to allow for the crystallisation of apatite. The glasses were prepared by a melt-quench route and powdered to obtain a particle size distribution between 125-250 µm. Glass-ceramics were prepared from heat-treatment for one hour at Tc1. In vitro apatite mineralisation was evaluated by immersing glass or glass-ceramic powders in Tris buffer, followed by XRD, ATR-FTIR, ICP-OES and MAS-NMR characterisation. XRD results showed diffraction peaks associated with apatite for glass-ceramics with P2O5 content above 3 mol%. Characterisation by ATR-FTIR showed characteristic Si-O-Si and Si-O-NBO bands for the glasses, while for the glass-ceramics narrow bands in the same regions suggested crystallisation of silicate phases, possibly sodium calcium silicates. Bands at 560-550 cm-1 confirmed the presence of apatite. After immersion in Tris buffer, Si4+ and Ca2+ release was comparable for glasses and glass-ceramics. ATR-FTIR, XRD and 19F MAS-NMR results confirmed that increasing P2O5 contents favoured fluorapatite mineralisation for glasses and glass-ceramics, while lower P2O5 contents favoured fluorite formation. Comparable ion release and apatite mineralisation for glass and glass-ceramics could be explained by the higher content of CaO and absence of Na2O usually present in bioactive glasses, as a higher CaO content is known to improve in vitro apatite mineralisation despite a reduced overall solubility of the glasses, and the presence of apatite in the glass-ceramics may have acted as nucleation sites for apatite precipitation during immersion.