Optimization Alternatives for Robust Model-based Design of Synthetic Biological Circuits**The research leading to these results has received funding from the European Union (FP7/2007-2013 under grant agreement n°604068), the Spanish Government (FEDER-CICYT DPI2011-524 28112-C04-01, DPI2014-55276-C5-1-R, DPI2015-70975-P) and the National Council of Scientific and Technologic Development of Brazil (BJT-304804/2014-2). Yadira Boada thanks also grant FPI/2013-3242 of the Universitat Politècnica de Valencia.