A new type of chemically modified graphene, EDTA-modified reduced graphene (EDTA-RG), was synthesized by silanization of graphene with N-(trimethoxysilylpropyl) ethylenediamine triacetic acid (EDTA-silane). It was found that the presence of EDTA on the graphene surface enables the formation of a very stable suspension of EDTA-RG in Nafion/ethanol solution. When deposited onto a glass carbon electrode surface, a very stable, uniform thin film of EDTA-RG−Nafion composite was successfully obtained. The electrochemical behavior of this EDTA-RG−Nafion modified electrode, electrochemical catalysis, ionic selectivity, and biocompatibility, have been investigated using a variety of electrochemical techniques. The ion selectivity was investigated by using a negatively charged probe [Fe(CN)6]3−/4−, a positively charged probe, Ru(bpy)32+, and two biomolecules, dopamine and ascorbic acid. The thin film of EDTA-RG−Nafion composite exhibits high ion selectivity. Performances of EDTA−graphene−Nafion modified electrodes ...