Paper Microfluidics Based on rGO/Polyaniline Nanofibers for Sensing Pyridoxine

Purpose: This study aims to develop a simple, low-cost, highly disposable paper-based electrochemical device to determine pyridoxine (vitamin B6). Methods: Dual-layer paper-based electrochemical devices (PEDs) were fabricated using wax and screen-printing techniques. The electrochemical sensing layer towards pyridoxine detection is prepared by modifying the working electrode with reduced graphene oxide (rGO) and electrodeposited polyaniline (PANI) nanofibers. Optimization of electrodeposition time was carried out to uniformly coat PANI nanofibers over rGO-modified PEDs. Surface morphologies of modified electrodes were examined by field emission scanning electron microscopy (FESEM), and PEDs were electrochemically characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Chronoamperometric responses of the modified electrode against pyridoxine were utilized for its quantification. Results: Morphological characterization of the modified FESEM indicates PANI’s porous and nanofiber network over rGO. The electrochemical characterization of the PEDs with CV and EIS reveals that the synergetic combination of PANI and rGO nanostructure possesses excellent electrochemical performance and enhanced electrocatalytic activity towards the oxidation of pyridoxine. The chronoamperometric (CA) responses of the PANI-rGO/PEDs towards pyridoxine showed a broader linear range from 5 to 1100 µM (R² = 0.97) and showed a lower detection limit of 1.43 µM at 0.50 V vs. pseudo-Ag/AgCl. Conclusion: The proposed multi-layer PEDs modified with a uniformly formed nanofiber network of PANI-rGO nanocomposite have the potential to be applied in developing a sensitive sensor for monitoring pyridoxine in a low-cost and disposable way. They are appropriate to be utilized in resource-limited settings.