Redox-Active Polyindole-Modified Electrode for Electrochemical Quantification of Uric Acid

Intrinsically conducting polymers are versatile materials for electrochemical sensing, yet polyindole (PIn) has remained largely unexplored for this purpose. Here, we report a PIn-modified glassy carbon electrode for the non-enzymatic determination of UA in neutral phosphate buffer.

PIn was synthesized by chemical oxidative polymerization in the presence of sulfonate dopants and deposited as a thin film on glassy carbon; physicochemical characterization confirmed a doped, conjugated, and nanostructured coating with a high effective surface area. The electrode showed a well-defined UA oxidation signal and, by chronoamperometry, a linear response over 0.01-0.10 mM with a sensitivity of 4.53 µA cm-2 mM-1 and a limit of detection of 4.0 M. Under the applied conditions, ascorbic acid, dopamine, glucose, and sodium chloride contributed only marginally to the response, and the sensor performed reliably in diluted human serum, with recoveries of 99.7-99.9% and relative standard deviations below 5%.