A facile and economic electrochemical sensor for methylmalonic acid: a potential biomarker for vitamin B12 deficiency

A facile and cost-effective method based on a modified pencil graphite electrode (PGE) has been developed for the sensing of methylmalonic acid (MMA). The electrode (Ag–PEDOT/PGE) was designed by the electrodeposition of Ag nanoparticles (NPs) on carbon fibre paper (CFP) coated with poly(3,4-ethylenedioxythiophene) (PEDOT). Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and other electroanalytical techniques were used to characterize the modified electrodes. The fabricated sensor showcased a wide linear dynamic range (0.50 pM–55 nM) and a low detection limit (0.16 pM). A sharp increase in anodic peak current shows the excellent rate of electron transfer arising from Ag–PEDOT and PGE. The developed electrode was effectively utilized towards electrochemical MMA determination in urine and human blood serum samples. The results obtained certainly indicate that the sensor has high selectivity, ensures rapid detection, is reproducible, and has high stability towards the quantification of MMA in real samples.