S1 Electroactive Interpenetrated Biohydrogels as Hybrid Materials Based on Conducting Polymers Brenda G. Molina, Ariadna Llampayas, Georgina Fabregat, Francesc Estrany,* Carlos Alemán,* and Juan Torras* Dr. B. G. Molina, Ms. A. Llampayas, Dr. G. Fabregat, Dr. F. Estrany, Prof. C. Alemán, Dr. J. Torras Departament d’Enginyeria Química, EEBE, Universitat Politècnica de Catalunya, C/ Eduard Maristany 10-14, 08019 Barcelona, Spain E-mail: francesc.estrany@upc.edu; carlos.aleman@upc.edu; joan.torras@upc.edu Dr. B. G. Molina, Dr. G. Fabregat, Dr. F. Estrany, Prof. C. Alemán, Dr. J. Torras Barcelona Research Center for Multiscale Science and Engineering, Universitat Politècnica de Catalunya, Eduard Maristany 10-14, 08019 Barcelona, Spain Abstract Different levels of interpenetration of poly(hydroxymethyl-3,4-ethylenedioxythiophene) (PHMeDOT) inside a poly-γ-glutamic acid (γPGA) biohydrogel matrix, previously loaded with microparticles of poly(3,4-ethylenedioxythiophene) (PEDOT), have been obtained. The degree of interpenetration has shown influence on the morphological and electrochemical properties of the resulting biohydrogel ([PEDOT/γPGA]PHMeDOT) with a maximum after 1 hour of PHMeDOT polymerization time. The high biocompatibility of all biohydrogel components, together with the combination of mechanical properties of γPGA hydrogels with the electrochemical properties of inter-connected microparticles of PEDOT, makes it a promising material for next generation of biosensors.