Electrocatalytic detection of dopamine at single-walled carbon nanotubes–iron (III) oxide nanoparticles platform

Electrochemical sensors using edge-plane pyrolytic graphite electrode (EPPGEs) modified with single-wall carbon nanotubes–iron (III) oxide (SWCNT/Fe2O3) nanoparticles for the sensitive detection of dopamine (DA) are described for the first time. The surface of the EPPGE-SWCNT–Fe2O3 was characterized using field emission scanning electron microscopy, atomic force microscopy and energy dispersive X-ray spectroscopy while the electrochemical properties were investigated using the cyclic voltammetry, square wave voltammetry and electrochemical impedance spectroscopy techniques. When compared with the bare electrode or electrodes without the Fe2O3 nanoparticles, the EPPGE-SWCNT–Fe2O3 gave best response (7 times more than bare EPPGE and 2-fold more than the other two modified electrodes) towards the detection of DA. Also, the EPPGE-SWCNT–Fe2O3 showed the best analytical performance for DA with an electron transfer rate constant of ∼0.26 cm s−1, a sensitivity of 3.44 μA μM−1, a limit of detection of 0.36 μM, a catalytic rate constant of 8.7 × 105 cm3 mol−1 s−1, and a diffusion coefficient of 3.5 × 10−5 cm2 s−1. This electrode can be reliably used to assay DA in its real drug composition.