Fabrication and electrochemical characterization of polydopamine redox polymer modified screen-printed carbon electrode for the detection of guanine

A modified screen-printed carbon electrode (SPCE) was fabricated by electrodeposition of dopamine to create a suitable polydopamine (PDA) redox polymer film for sensing applications. The fabricated sensor, designated as PDA-SPCE, was characterized by electrochemical impedance spectroscopy, contact angle measurements and chronoamperometry. The surface coverage of redox species on the polymer film was optimized and found to be ∼6.1 × 10−6 mol cm−2. Using square wave voltammetry, the PDA-SPCE was used to facilitate and observe the electrocatalytic oxidation of guanine at different concentrations. A calibration curve for guanine was constructed, with a sensitivity of 90.5 μA μM−1 cm−2 and a limit of detection (based on 3× the baseline noise) of 15.8 μM.