A highly selective bifunctional nanosensor based on nanocellulose and 3D polypyrrole decorated with silver-gold bimetallic alloy to simultaneously detect methotrexate and ciprofloxacin

An electrochemical sensing platform for the simultaneous detection of methotrexate (MTX) and Ciprofloxacin (CIF) has been presented using nanocellulose and 3dimensional polypyrrole (NC-3DPPY) hybridized silver-gold bimetallic alloy nanoparticle (Ag-Au). The NC-3DPPY composites and Ag-Au bimetallic alloys were prepared by acid hydrolysis and chemical reduction, respectively. The nanocomposite structure of NC-3DPPY@Ag-Au was prepared through ultrasonication, and the electrochemical performances of the nanocomposites were elucidated by cyclic voltammetry (CV) and square wave voltammetry (SWV). Field emission scanning electron microscopy (FESEM) and High-resolution transmission electron microscopy (HR-TEM) analysis showed that the as-prepared nanocomposites possess a porous structure, and the nanoparticles are interconnected. The thermogravimetric analysis (TGA) results revealed that the NC-3DPPY@Ag-Au nanocomposite has higher thermal stability than NC and NC-3DPPY. The electrocatalytic efficiency of the nanocomposites was evaluated by oxygen evaluation reaction (OER), and the binding interactions between NC-3DPPY@Ag-Au with MTX and CIF were studied using a computational technique. At the optimized values of scan rate, pH, and supporting electrolyte conditions, the fabricated sensor demonstrated a broad linear detection ranges of 5–350 µM and 0.5–50 µM, with a low limit of detection (LOD) of 0.062 and 0.017 µM for MTX and CIF, respectively. The proposed simultaneous electrochemical sensor exhibits high stability, excellent reproducibility and selectivity to detect MTX and CIF in the presence of common interfering species. Our study showed excellent analytical performances for trace level detection of MTX and CIF in simulated blood serum, tablets, and water samples with satisfactory recoveries.