Determination of quercetin in biological samples using graphite paste electrode modified with poly(dopamine quinone-chromium(III) complex)@cobalt hierarchical cabbage flower-like structure mesoporous nanocomposite

In this research, a novel, sensitive, and efficient electrochemical sensor was built for the first time based on Co cabbage flower-like structure decorated on poly(dopamine quinone-chromium(III) complex) nanocomposite (p[DqCrC]@Co-NC) to accurately determine quercetin (QR) in aqueous and biological samples. The developed nanocomposite was characterized by Fourier-transform infrared spectroscopy (FT-IR), field emission-scanning electron microscopy (FE-SEM), Brunauer-Emmett-Teller (BET), and energy-dispersive X-ray spectroscopy (EDS). Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and differential pulse voltammetry (DPV) techniques were employed for quantitative and qualitative analysis of QR. The oxidation of QR proceeded reversibly with the participation of two electrons and two protons as controlled by the analyte adsorption on the surface of the electrode. This new sensing system exhibited a wide linear response range of 0.01–150 μM with a limit of detection of 14 nM (S/N = 3) and a limit of quantification of 48.7 nM. The analytical performance of p[DqCrC]@Co-NC, when assessed in real samples (such as human blood serum and urine), was reliable with relative recoveries between 98.8% and 105%. The fabricated sensor presented good repeatability with a favorable relative standard deviation of 5.1%. This electrochemical sensor was recognized as a promising platform for determining QR in biological samples. • Poly(dopamine quinone-chromium(III) complex)@Co nanocomposite was synthesized. • The nanocomposite was used for the modification of GPE. • Highly sensitive and selective determination of quercetin was obtained. • A linear response range of 0.01–150 μM with LOD of 14 nM (S/N = 3) was achieved. • The sensor was also accurate and sensitive for quercetin quantification in real samples.