1. Polymer Engineering Department, University of Minho, Campus de Azurém, 4800-058 Guimarães, Portugal; 3B's Research GroupBiomaterials, Biodegradables and Biomimetics, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal; and Center for Biomaterials, Universidad Politécnica de Valencia, P.O. Box 22012, E-46071 Valencia, Spain