A chitosan/rGO/Fe₃O₄-modified electrode for sensitive cholesterol determination in blood serum

Cholesterol (Ch) plays a crucial role in the cell membrane structure and metabolic processes, including hormone and bile acid biosynthesis. However, an abnormally high Ch level in the blood is a major risk factor for cardiovascular disease, the leading cause of global mortality, highlighting the need for accurate and sensitive Ch detection. In this study, we designed a straightforward, cost-effective, and robust quantitative approach for Ch detection using a chitosan/reduced graphene oxide/magnetite (CS/rGO/Fe₃O₄)-modified copper-printed circuit board (Cu-PCB) electrode. The proposed electrode was fabricated by depositing a CS/rGO/Fe₃O₄ composite onto Cu-PCB's surface via the electrodeposition technique. The obtained electrode was characterized using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Raman spectroscopy, field-emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), and cyclic voltammetry (CV) techniques. The proposed electrode was used for the detection of cholesterol via CV, which exhibited a linear range of 100-300 mg dL^-1, sensitivity of 0.160 µA µM^-1 cm^-2, limit of detection of 0.149 µM, and limit of quantification of 0.496 µM. The fabricated electrode also displayed satisfactory results when detecting cholesterol in blood serum samples compared with conventional laboratory analysis. Finally, the developed electrode showed excellent agreement with laboratory reference methods (R ² = 0.99947), confirming the accuracy and practical applicability of the proposed platform for serum cholesterol analysis.