1. Laboratory of General Biochemistry and Physical Pharmacy, Department of Pharmaceutics, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium, Section on Tissue Biophysics and Biomimetics, NICHD, National Institutes of Health, 13 South Drive, Bethesda, Maryland 20892-5772, Department of Chemical engineering, Queen's University, Kingston, Ontario, Canada, and Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, University Utrecht, 3508TB Utrecht, The Netherlands