Figure 3. Optimization studies of the BC-based electrochemical biosensor.

(A) Modification of the WE to anchor ACE2 using 2 mg mL⁻¹ G-PEG (black circles) or1 mg mL⁻¹ PEI (red circles).

(B) Performance of the electrochemical biosensor modified with 0.5% (m/v) Nafion (black circles), modified with 0.5% (m/v) chitosan (red circles), and without membrane layer (blue circles).

(C) Effect of Nafion concentration on the sensitivity of the method: 0.0% (black circles), 0.5% (m/v; red circles), 1.0% (m/v; blue circles), 1.5% (m/v; purple circles), and 2.0% (m/v; green circles).

(D) Incubation time study with time ranging from 3 to 7 min, using the BC-based biosensor. All experiments were carried out in triplicate (n = 3) using SP as a target in a concentration range from 10 fg mL⁻¹ to 10 pg mL⁻¹ at room temperature. The error bars correspond to the standard deviation. Potentiometric measurements were recorded in 0.1 mol L⁻¹ PBS during 300 s of analysis.