1. Department of Biomaterials; Radboud University Medical Center; Philips van Leydenlaan 25 6525 EX Nijmegen The Netherlands
2. Dipartimento di Chimica; Università degli Studi di Bari Aldo Moro; Via E. Orabona 4 70125 Bari Italy
3. Institute of Science and Technology for Ceramics (ISTEC); National Research Council (CNR); Via Granarolo 64 48018 Faenza Italy
4. Department of Nuclear Medicine; Radboud University Medical Center; Geert Grooteplein Zuid 10 6525 AG Nijmegen The Netherlands