Construction of Poly(methylene blue)/Copper Nanowires Modified Electrode for High-Performance Luteolin Sensing

A poly (methylene blue)/copper nanowires modified nano-carbon paste electrode (PMB/CuNWs@nano-CPE) was developed for ultra-sensitive detection of luteolin. The morphology of copper nanowires was characterized by transmission electron microscopy (TEM). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were utilized to investigate the electrochemical properties of the fabricated electrodes. In comparison with bare nano-carbon paste electrodes (nano-CPE), the PMB/CuNWs@nano-CPE presented better electrocatalytic activity towards luteolin, including reduced oxidation peak potential and enhanced oxidation peak current. The influencing factors on sensitivity were discussed, such as instrumental parameters, concentration of methylene blue, electropolymerization cycles, the amount of copper nanowires, pH value, accumulation potential and accumulation time. Under optimal conditions, two linear calibration ranges of 0.5 nM−0.01 μM and 0.01 μM−1 μM and the detection limit (LOD) of 0.1 nM (S/N = 3) were obtained for luteolin. The satisfying results were achieved for the determination of luteolin in Chinese medicine capsule samples.