To detect bacteria, 100 mL bacteria dilutions with different
concentrations prepared in Tris–HCl buffer was dropped on the
sAMP modified gold electrode surface, incubated for 30 min. The
electrode was then washed twice using Tris–HCl buffer. Detection
was accomplished by probing the Faradaic electron impedance of
the potassium ferricyanide redox pair at the sAMP modified
electrode before and after incubation with bacteria, as described in
supplementary information (SI).