Ultrafast Microwave-Synthesized 2D/1D MnO2/Carbon Nanotube Hybrid for Bilirubin Detection in Simulated Blood Serum

Hybridization of carbon nanotubes (CNTs) and manganese dioxide (MnO2) integrates the biocompatibility and outstanding electrocatalytic activity of MnO2 with the exceptional conductivity of CNTs, thus providing a superior synergistic sensing platform for the detection of biomolecules. However, the existing methods for synthesizing MnO2/CNT hybrids are complex and inefficient, resulting in low yields and limited surface functionalities. Hence, in this study, we present a low-cost and ultrafast solid-phase synthesis of the MnO2/CNT hybrid using a facile microwave technique to detect a crucial biomolecule bilirubin. The successful synthesis of the MnO2/CNT hybrid is confirmed through characteristic Raman and X-ray diffraction peaks, while morphology is analyzed by imaging techniques such as FESEM and HRTEM. The MnO2/CNT/nickel foam (NF) sensor is thereafter used for the electrochemical detection of bilirubin. The sensor demonstrates a wide linear detection range from 10 nM to 1 mM, with a sensitivity of 6.87 mA nM–1 cm–2 toward bilirubin, as determined through the differential pulse voltammetry technique. The lower limit of detection is noted at 3.3 nM (=3.3 S/m). Furthermore, the as-fabricated sensor showcases high selectivity against the interfering species. Real-time analysis conducted in simulated blood serum using the standard addition method reveals an outstanding recovery percentage of approximately 98%. The conductive MnO2/CNT hybrid interacts robustly with bilirubin, aided by the porous NF substrate for stability, catalytic activity, and rapid electron transfer, enabling sensitive bilirubin detection. The work provides an ultrafast, low-cost, and high-yield solid-phase microwave synthesis of MnO2/CNT hybrid material and broadens its application in the detection of biological specimens for clinical diagnosis and biomedical research.