Synergistic micrometer flower bloom: Quercetin electrochemical sensing platform constructed from CuO-C/NiCo2O4 composite material

The pharmacological, biological, and biochemical properties of quercetin hold significant implications in the realms of medicinal chemistry, biochemistry, and clinical medicine. In this study, metal–organic framework (Cu-MOF), nickel nitrate, and cobalt nitrate were used as raw materials, and metal-oxide (CuO-C/NiCo₂O₄) composites containing carbonaceous and floral structures were prepared by annealing and co-precipitation techniques. The CuO-C/NiCo₂O₄/GCE composite electrode was acquired by embellishing CuO-C/NiCo₂O₄ on polished glassy carbon electrodes (GCE) using dropwise coating. The synthesized CuO-C/NiCo₂O₄ was investigated through: (i) scanning electron microscopy (SEM) imaging for morphological evaluation, (ii) X-ray diffraction (XRD) for phase identification, and (iii) X-ray photoelectron spectroscopy (XPS) for elemental state determination. The results revealed that the CuO-C/NiCo₂O₄ composites have a loose and porous surface, an elevated active surface area, high electrical conductivity, and electrocatalytic properties. Based on this result, an electrochemically novel sensor for the detection of quercetin using CuO-C/NiCo₂O₄ composites was developed. The sensor displayed high reproducibility, redox stability, and anti-interference capability in the detection of quercetin. In addition, the peak current measured by this sensor was linearly correlated with the density of quercetin, exhibiting a wide linearity response from 0.1 to 20 μM with an ultralow detection limit of 0.092 μM. These advantages originate in the synergy between CuO-C and NiCo₂O₄. Currently, the constructed electrochemical sensor has been successfully employed for the determination of quercetin content in ginkgo biloba leaf.