Prof. Aldo R Boccaccini | University of Erlangen-Nuremberg | Germany
Dr.-Ing. Kai Zheng
Bioactive glass nanoparticles (BGN) are a versatile system for a variety of biomedical applications including bone repair/regeneration, wound healing, and anticancer treatment [1,2]. BGN can be used as building blocks of functional scaffolds or coatings as well as can act as platforms for delivering drugs (e.g., antibiotics, growth factors) and biologically active ions (e.g., Ca2+, Cu2+) . However, it is still challenging to develop ion doped BGN of high dispersity and chemical homogeneity that are desired in specific applications (e.g., drug delivery) . We developed a series of sol-gel based approaches, e.g., a modified Stöber method, surface modification, to synthesize such preferred ion doped BGN. The composition (e.g., type and concentration of doped ions) and morphology (e.g., particle size, porosity) of BGN can be tailored conveniently by tuning processing parameters. Particularly, the osteogenesis, angiogenesis or antibacterial activity of BGN could be promoted by incorporating corresponding biologically active ions. Incorporation of BGN into polymer matrices (e.g., coatings, hydrogels) to fabricate functional scaffolds or orthopedic implants was also investigated. BGN show great potential in applications related to tissue regeneration or nanomedicine. This presentation will summarize recent developments in this field highlighting also future challenges and opportunities for the further applications of BGN in medicine.
 V. Miguez-Pacheco, L.L. Hench, A.R. Boccaccini, Bioactive glasses beyond bone and teeth: Emerging applications in contact with soft tissues, Acta Biomater. 13 (2015) 1–15. doi:10.1016/j.actbio.2014.11.004.
 K. Zheng, A.R. Boccaccini, Sol-gel processing of bioactive glass nanoparticles: A review, Adv. Colloid Interface Sci. 249 (2017) 363–373. doi:10.1016/j.cis.2017.03.008.
 A. Hoppe, N.S. Güldal, A.R. Boccaccini, A review of the biological response to ionic dissolution products from bioactive glasses and glass-ceramics., Biomaterials. 32 (2011) 2757–2774. doi:10.1016/j.biomaterials.2011.01.004.
Effect of TES buffer on the quality of hydroxyapatite formed on 45S5 based bioactive glass-ceramic scaffolds
PhD Diana Horkavcová | University of Chemistry and Technology Prague, Department of Glass and Ceramics | Czech Republic
Dr.-Ing. Dana Rohanová | University of Chemistry and Technology Prague, Department of Glass and Ceramics | Czech Republic
Katharina Schuhladen | University of Erlangen-Nuremberg | Germany
Adam Stříbny | University of Chemistry and Technology Prague | Czech Republic
Prof. Aldo R Boccaccini | University of Erlangen-Nuremberg
Prof. Aleš Helebrant | University of Chemistry and Technology in Prague | Czech Republic
The aim of this work was to study the interactions of bioactive glass-ceramic scaffolds (Bioglass® derived) with simulated body fluid (SBF) buffered by TES (2-[(2-Hydroxy-1,1-bis(hydroxymethyl)ethyl)amino]ethanesulfonic acid) (from the family of the Good´s buffers). TES is an alternative buffer to the commonly tested TRIS buffer (tris(hydroxymethyl)aminomethane) (replacement in SBF, ISO 23317). The in vitro test was carried out under static-dynamic conditions with daily exchange of the SBF solution. The pH measurement and the concentrations of Si, Ca and P in the SBF eluate showed very similar results as in the case of the TRIS buffer investigated previously. However, the material characterization by SEM/EDS, XRD, XRF and BET confirmed the different morphology and the kinetics of hydroxyapatite (HAp) formation compared to the results obtained using SBF solution buffered with TRIS.
Silicate, borosilicate and borate bioactive glasses: A comparison of the dissolution behavior under different conditions
Prof. Leena Hupa | Åbo Akademi University | Finland
Prof. Aldo R Boccaccini | Friedrich-Alexander-Universität Erlangen-Nürnberg | Germany
Key properties of bioactive glasses include their ability to dissolve and release ions when immersed in an aqueous environment, as well as the formation of an apatite surface layer on the glass during dissolution . Due to the lower chemical durability of borate glasses and their ability to transform rapidly to hydroxyapatite, an increasing amount of research has started to focus on the use of borate glasses. Additionally, borosilicate bioactive glasses are being developed by replacing partly Si by B. By varying the ratio of silicon to boron oxide, it is possible to tailor the dissolution and transformation rate of these glasses .
The dissolution of silicate, borate and borosilicate bioactive glass particles (500-300 µm) was measured with a continuous flow-through-cell connected with a peristaltic pump with a pumping rate of 0.2 ml/min. Additionally, the samples were placed in SBF under static conditions following the standard protocol by Kokubo . In order to compare the ion release kinetics under dynamic and static conditions, ICP measurements were done after immersing the glasses in SBF for up to 48h. The results show that the silicate glass dissolves five times faster, whereas the borate glass dissolves 10 times faster under dynamic conditions compared to static conditions. Furthermore, differences in the release profiles were found. The implication of such different bioreactivity of B containing glasses for applications in hard and soft tissue engineering will be discussed.
Abo Akademi's Johan Gadolin Scholarship is gratefully acknowledged for financial support.
 D. S. Brauer, Angew. Chemie Int. Ed., 2015, 54, 4160–4181.
 Y. Li, M. N. Rahaman, Q. Fu, B. S. Bal, A. Yao and D. E. Day, J. Am. Ceram. Soc., 2007, 90, 3804–3810.
 T. Kokubo and T. Hiroaki, Biomaterials, 2006, 27, 2907–2915.
Dissolution of phosphate glasses for therapeutic ion release: the effect of cobalt on hydrolysis
M.Sc. Dahiana Andrea Avila Salazar | Otto Schott Institute of Materials Research (OSIM), FSU Jena | Germany
Dr. rer. nat. Peter Bellstedt | Germany
M.Sc. Atsuhiro Miura | Japan
Prof. Toshihiro Kasuga | Japan
Prof. Delia S. Brauer | Germany
Structural changes in phosphate glasses have been found to tune the glass degradation rate, which is of interest for therapeutic applications such as drug delivery. Therefore, getting insight into the mechanism of hydrolysis is of importance. In the present work, structural characterization via P-31 MAS NMR of the glass system 45P2O5–(x-y)CaO–(55-x)Na2O–yCoO (x: 25 to 40, y: 0 to 10 mol%) was correlated with dissolution kinetics through time-dependent P-31 NMR, pH and ICP-OES measurements, run in deionised water, Tris (pH: 7.4, 7.9) and EDTA (pH: 10.0). Here the paramagnetic nature of Co2+ was exploited; paramagnetic centres broaden the P-31 resonance, providing direct information about the role of the metal complex in the hydrolysis process. The trimetaphosphate ring and orthophosphate as predominant structures in solution, except in EDTA, indicated fast hydrolysis of chains and exhibited paramagnetic broadening, thus suggesting that the phosphate group may be directly coordinated to Co2+. The rate of hydrolysis was proportional to the stability of the respective phosphate complex, with stronger complexes for the phosphate chains than for the rings. A competition between the solvent and phosphate species for the metal ion occurred following the trend: EDTA> Tris (pH: 7.9)> Tris (pH: 7.4)> deionised water. In conclusion, the catalytic effect of the metal ions may consist in turning the phosphorus atom into a suitable electrophile, for a subsequent nucleophilic attack by water.