One-step synthesis of functional pNR/rGO composite as a building block for enhanced ascorbic acid biosensing

An electrochemical sensor for ascorbic acid (AA) was prepared via an one-step electrochemical approach by reducing graphene oxide (rGO) and co-polymerizing neutral red (NR) and rGO to form a pNR/rGO hybrid film on the glassy carbon electrode (pNR/rGO-GCE). Structures and properties of the obtained pNR/rGO film were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) and UV-vis techniques. A significant decrease of charge-transfer resistance (Rct) from over 20,000 Ω for pNR-GCE to 130 Ω for pNR/rGO-GCE was validated by electrochemical impedance spectroscopy (EIS) measurement. Particularly, electrochemical data revealed that pNR/rGO film could effectively enhance the electron transfer between AA and electrode, and thus reduce the overpotential of AA oxidation. Two linear regression areas with 0.05-0.75 mM and 0.9-24.9 mM, detection limit with 1.4 μM, and stability over 2 weeks were obtained. The coexisting distractions such as dopamine, uric acid and glucose were detected and eliminated. Moreover, the pNR/rGO-GCE gave the same determination results as that obtained with HPLC when measuring real samples, including vitamin C beverage and human serum.