An ultrasensitive non-enzymatic bilirubin electrochemical sensor based on a polyvinylpyrrolidone-functionalized single-walled carbon nanotube modified electrode surface

Abstract

Hyperbilirubinemia, characterized by elevated bilirubin levels, is a primary cause of neonatal jaundice and necessitates rapid and accurate detection to enable timely clinical intervention. Herein, we report the development of a binder-free, non-enzymatic electrochemical sensor for bilirubin quantification, fabricated by modifying a glassy carbon electrode (GCE) with a polyvinylpyrrolidone (PVP)-functionalized single-walled carbon nanotube (SWCNT) composite. Unlike conventional Nafion-based systems, this design avoids binder-induced sensitivity loss at physiological pH while leveraging the intrinsic conductivity and large surface area of SWCNTs. Comparative evaluation with other carbon-based materials confirmed the superior electrocatalytic performance of the pristine SWCNTs. Functionalization with PVP further enhanced nanotube dispersion, hydrophilicity, and electron transfer kinetics. Importantly, the removal of residual metal impurities from the pristine SWCNTs did not compromise their electrocatalytic response. Voltammetry techniques revealed dual oxidation peaks corresponding to bilirubin and biliverdin with low detection limits (4.25 μM and 2.96 μM) overcoming the clinical thresholds across a wide linear range (0.5–50 μM). The sensor exhibited excellent selectivity, validated through interference and real-sample analyses. This simple yet robust platform offers a cost-effective and scalable route towards portable point-of-care diagnostics for neonatal jaundice management.