Chromone Indole‐Pyrazole Cobalt Nanoparticle‐Based Electrochemical Immunosensor for Insulin Antibody Detection

A sensitive electrochemical immunosensor is developed for detecting insulin antibodies, predictive biomarkers of early type 1 diabetes in genetically predisposed individuals. The sensor is prepared by immobilizing chromone‐indole‐pyrazole cobalt nanoparticles (CIP‐CoNPs) onto a platinum electrode, followed by insulin antigen attachment and surface blocking with bovine serum albumin. The CIP ligand, with its electron‐rich π‐system and strong coordination sites, enhances electron transfer, nanoparticle stability, and biomolecule immobilization, boosting sensitivity and selectivity. The nanoparticles are synthesized via a green route using lemon peel extract, increasing surface area and electrochemical conductivity. Scanning electron microscopy confirms a spherical morphology. Fabrication steps are characterized using cyclic voltammetry and electrochemical impedance spectroscopy, linking the nanocomposite structure to changes in electrochemical properties during sensor assembly. Under optimized conditions, square wave voltammetry detects insulin antibodies over a linear range of 0.001–50 ng mL ^{− 1} . The sensor achieves a detection limit of 0.34 ng mL ^{− 1} and a sensitivity of 5.60 μA ng mL ^{− 1} . It shows excellent reproducibility and accuracy in synthetic human serum, with recoveries of 98.7–101.3% and relative standard deviations of 1.19–2.34%, confirming strong potential for clinical application.