1. Institute of Biomaterials, Department of Materials Science and Engineering, University of Erlangen-Nuremberg, 91058 Erlangen, Germany
2. Instituto de Ciencia de Materiales de Sevilla (CSIC-Universidad de Sevilla), 41092 Seville, Spain
3. † Current address: Departamento de Ingeniería y Ciencia de los Materiales y del Transporte Universidad de Sevilla, 41092 Seville, Spain
4. † Special collection papers can be found online at http://www.minsocam.org/MSA/AmMin/special-collections.html.
5. Institute of Particle Technology, Department of Chemical and Biological Engineering, University of Erlangen-Nuremberg, 91058 Erlangen, Germany
6. * E-mail: aldo.boccaccini@ww.uni-erlangen.de