Trace level electrochemical determination of the neurotransmitter dopamine in biological samples based on iron oxide nanoparticle decorated graphene sheets

In this paper, we report the highly selective and sensitive electrochemical determination of dopamine (DA) based on an iron oxide nanoparticle-(Fe2O3 NP) capped graphene sheet (GRS) modified glassy carbon electrode (GCE). The Fe2O3 NPs were synthesized by a pyrophoric technique and their nanocomposite with GRS was prepared by a simple sonochemical method. The as-prepared Fe2O3 NP/GRS nanocomposite was characterized using scanning electron microscopy, electron dispersive X-ray spectroscopy, Raman spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy and electrochemical impedance spectroscopy. As expected, the proposed sensor exhibits a wide linear range from 0.01 to 195.18, a low detection limit (LOD) of 0.004 mu M for the DPV technique and a broad linear range from 0.006 to 635 mu M, and a very low detection limit of 0.001 mu M for the amperometric technique. Moreover, it shows excellent selectivity of DA even in the presence of a 20-fold higher concentration of potential interferences. The practical applicability of the reported sensor was recorded in human serum and urine samples. Finally, all electrochemical studies confirmed the excellent electrocatalytic activity of the Fe2O3 NP/GRS nanocomposite as a DA sensor.