[en] Full text: The most used therapy for the treatment of bladder cancer is the intravesical administration of Bacillus Calmette-Gueri (BCG) associated with transurethral resection. However, a significant number of patients have shown intolerance, besides potentially fatal complications. In this work, we aim to develop graphene oxide (GO) hybrids for administration of metformin and interference RNA (siRNA) for VEGF (vascular endothelial growth factor). GO was chemically modified for drug entrapment. The hybrids were characterized by physical and chemical methods such as infrared absorption spectroscopy (FTIR), RAMAN spectroscopy, X-ray photoelectron spectroscopy (XPS) and zeta potential. GO presented a zeta potential of -31.2 mV. In order to make GO positively charged, GO was reacted with PEI, a positively charged polymer. GO-PEI hybrid showed a zeta potential of +31.2 mV. Another hybrid containing PEG was synthesized, GO-PEG-PEI, since the presence of PEG in the hybrid could decrease a possible cytotoxicity related to the GO-PEI. The pegylation of nanoparticles offer several advantages, such as the decrease in toxicity, the activation of the immune responses and clearance. Future investigations will be done regarding the entrapment of Metformin and siRNA into the hybrids, as well as the evaluation of in vivo antitumoral activity. (author)