Highly dispersed carbon nanotube in new ionic liquid-graphene oxides aqueous dispersions for ultrasensitive dopamine detection

Graphite oxide (GO) is a pH-dependent amphiphile with hydrophilic edges and a more hydrophobic basal plane. It was found that when the hydrophobic prototype ionic liquid (IL) of 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF 6 ]) was added into GO water, it experienced changes from coagulation to being redispersed in water phase by constantly turning its pH to alkali condition. Then new aqueous dispersions of GO-[BMIM][PF 6 ] “water” formed after facile sonicate. The introduction of [BMIM][PF 6 ] not only minimize the defects of poor electrical conductivity of GO and more interesting is that the carbon nanotube (CNT) can be highly dispersed in this GO-[BMIM][PF 6 ] water through a simple and facile ultrasonic method at room temperature, forming a new composite of GO-[BMIM][PF 6 ]-CNT with high dispersibility. This novel composite enhanced its electrochemical signal obviously in the measurement of dopamine (DA) in biological systems and exhibited a wider linear response ranging from 8.0   ×   10 −12 –1.5   ×   10 −5   M. The detection limit of 3.0   ×   10 −12   M at a signal to-noise ratio of 3 was two orders of magnitude lower than that reported previously.