Highly sensitive and selective electrochemical sensor for detection of vitamin B12 using an Au/PPy/FMNPs@TD-modified electrode

Abstract

A new electrochemical sensor for sensitive and selective detection of vitamin B12 (VB12) was constructed by the electropolymerization of pyrrole (Py) in the presence of ferromagnetic nanoparticle-incorporated triazine dendrimer (FMNPs@TD) on a gold electrode (Au). The gold/polypyrrole/ferromagnetic nanoparticles/triazine dendrimer (Au/PPy/FMNPs@TD) electrode showed electrocatalytic activity for the reduction of VB12 in Britton-Robinson buffers. The performance and interaction of the Au/PPy/FMNPs@TD with VB12 were investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), differential pulse voltammetric (DPV), UV–vis spectroelectrochemistry, and density functional theory calculations. The resulting sensor exhibited excellent performance for determination of VB12 with a wide linear range (2.50 nM–0.5 μM), highly reproducible response (RSD of 2.3%), low percentage of interferences, and long-term stability. The limit of detection (LOD) and limit of quantitation (LOQ) values for the determination of VB12 were 0.91 and 3.00 nM, respectively. The electron transfer rate constants (ks), charge transfer coefficient (α), surface concentrations of electroactive species (Г), and disproportionation equilibrium constant (KD) for Au/PPy/FMNPs@TD-modified electrodes were calculated. Finally, the constructed sensor was applied to the determination of VB12 in food samples.