Glasses and glass ceramics consist of undercooled, partially or fully amorphous materials and are used since thousands of years for their intriguing properties. Certain glass compositions known as Bioglass® or bioactive glasses were even found to form a tight bond with living bone [1]. These materials can be applied for bone repair and regeneration of defects arising from trauma, tumor and osteoporosis [2]. It has been suggested that the use of bioglass nanoparticles would strongly enhance control on degradation and bioactivity. Unfortunately, solid state reactions and sol-gel processes can be limiting in terms of composition, high remaining solvent content and generally require an annealing or sintering step after preparation [3]. We recently have shown that a direct synthesis of complex materials such as salts [4,5] or glasses consisting of 5 or more elements [6] is possible in a high temperature environment, i.e. flame spray synthesis. 45S5, 45S5F and 77S-type of bioactive glass was synthesized and characterized. The as-prepared bioactive glasses consisted of XRD-amorphous nanoparticles with a primary particle size of 20-80 nm (SSA_BET 70-200m²/g depending on composition) . After immersion of 45S5 type bioactive glass nanoparticles in simulated body fluid (SBF) for 7 days, Raman spectroscopy and electron microcopy was used to assess the surface of the material. The formation of a nanosized crystalline carbonated apatite layer was observed thus confirming the bioactivity of the material (Fig 1) [6].

References: [1] L.L. Hench, J. Biomed. Mat. Res. 5:117-41 (1971), [2] T. Nakamura, T. Yamamuro, S. Higashi, T. Kokubo, S. Itoo, J. Biomed. Mat. Res. 19:685-98 (1985), [3] R. Roy, Science (1987) [4] S. Loher, W.J. Stark, M. Maciejewski, A. Baiker, S.E. Pratsinis, D. Reichardt, F. Maspero, D. Günther, Chem. Mater. 17 (1), 36-42 (2005), [5] R.N. Grass, W.J. Stark, Chem. Commun., 14, 1767-1769 (2005), [6] T.J. Brunner, R.N. Grass, W.J. Stark, Chem. Commun., 13, 1384-86 (2006)

Fig.1: SEM image of Bioglass 45S5 after incubation in SBF.