Fig. 3. Top: schematic explaining the sensing mechanism of LS–rGO/GCE sensors. (a) CV curves of 100 μM DA in 0.1 M PBS (pH = 7.0) at a scan rate of 50 mV s⁻¹ on GCE, rGO/GCE (0.5 mg mL⁻¹), LS–rGO/GCE (0.25 mg mL⁻¹), and LS–rGO/GCE (0.5 mg mL⁻¹). (b) Nyquist plots of 5 mM [Fe (CN)₆]^4−/3− and 0.1 M KCL in 0.1 M PBS on GCE, rGO/GCE, and LS–rGO. Frequency range of 0.1 Hz to 1000 kHz. The amplitude of 5 mV was applied.