FeMoO4 based, enzyme-free electrochemical biosensor for ultrasensitive detection of norepinephrine

Herein, FeMoO4 (FM) nanorods were synthesized by a template-free, facile, hydrothermal method in an aqueous medium. The surface morphology of FeMoO4 was identified with field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). X-ray diffraction (XRD) was performed to identify the crystallographic nature of the as-synthesized FeMoO4. The as-synthesized material was used as an active electrode material for the oxidation of a neurotransmitter (i.e. norepinephrine (NE)) by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. FeMoO4 possesses polycrystallanity and bimetallic character, which helps to enhance the performance of the FM/GCE as compared to the GCE. The enhanced performance was also due to the formation of Fe (II)-dioxygen complexes, which catalyze the oxidation of NE. Meticulous observations taken from CV studies proved the diffusion-controlled nature of the reaction with a diffusion coefficient of 1.10×10−4 cm2/s and a standard heterogeneous rate constant of 4.078×10−3 cm/s. The amperometric response of NE on the FM/GCE showed a linear increase in the current between 5.0×10−8 M and 2.0×10−4 M with a detection limit of 3.7×10−9 M. In the amperometric study, the time required to reach the 98% steady state response, after successive additions of 50 nM NE, was less than 3 s. The FM/GCE showed good sensitivity, and stability for the determination of NE.