Selective detection of bilirubin in blood serum using UV–Vis spectroelectrochemistry technique with CeO₂-CNF/ITO transparent electrode

A UV–Vis spectroelectrochemical sensor is fabricated for the selective detection of the bilirubin (BR) liver-biomarker. The novel CeO₂-capped carbon nanofibers (CNFs) coated over an indium tin oxide substrate is used as the sensing electrode. CNFs are grown over CeO₂ nanoparticles using acetylene as the carbon source. Measurements are based on the cyclic voltammetry coupled UV–Vis spectroscopy technique, where BR is electro-oxidized to purpurin that is detected at 316 nm in the absorbance spectra. A linear calibration plot (R² > 0.99) is recorded over the BR concentration range of 5 – 200 µM in carbonate buffer at pH 10. The limit of detection of the sensor is determined as 4.49 µM. The CeO₂-CNF improves the electrocatalytic activity and electroconductivity of the electrode, thereby decreasing the charge transfer resistance for BR oxidation. Owing to its dual selectivity, the hybrid SEC approach eliminates the interferences from uric acid, ascorbic acid, glucose, and the other quickly oxidized biomolecules. The sensor is successfully tested in biological samples.