1. Institute for Biomedical Engineering and Department of Materials, Swiss Federal Institute of Technology (ETH) and University of Zurich, Moussonstrasse 18, CH-8044 Zurich, Switzerland, School of Pharmacy and Pharmaceutical Sciences, University of Manchester, Coupland III, Coupland Street/Oxford Road, M13 9PL Manchester, United Kingdom, and Institute for Polymers and Department of Materials, Swiss Federal Institute of Technology (ETH), Universitätstrasse 6, CH-8092 Zurich, Switzerland