Graphene-Carbon Nanotube Nanocomposite-Based Selective Nonenzymatic Electrochemical Detection of Ferrum Metallicum in Biological Fluid

Highly sensitive, nonenzymatic electrochemical sensor has been developed for the detection of Ferrum Metallicum, a homeopathic iron formulation. The sensor architecture integrates a nickel foam functionalized with an activated graphene–carbon nanotube (NAG-CNT) composite, yielding a defect-rich, graphitic nanostructure as confirmed by transmission electron microscopy (TEM), Fourier transform infrared (FTIR), Raman spectroscopies, and X-ray diffraction. Enhanced electroactive surface area facilitates rapid charge transfer, as validated through cyclic voltammetry and chronocoulometry. Electrochemical characterization using differential pulse voltammetry within a three-electrode system demonstrated a broad linear detection range (50 nM–200 mM), a low detection limit ∼13.12 nM, and high sensitivity (25 mA mM–1 cm–2). Mechanistic studies revealed an oxidation process governed by diffusion and proton transfer. The sensor exhibited remarkable selectivity against common interferents and achieved quantitative recovery (>97%) with excellent reproducibility (≤5% RSD) in spiked serum samples. These findings underscore its potential for pharmaceutical quality control and point-of-care diagnostic applications.