1. Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus UAB, 08193 Bellaterra, Catalonia Spain
2. Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), E-08193 Barcelona, Spain
3. CNR-NANO Istituto Nanoscienze, Centro S3, I-41125 Modena, Italy
4. ICREA, Passeig Lluís Companys 23, 08010 Barcelona, Spain