Unless otherwise noted, all characterization experiments were performed with the cysteine
modified peptide, WK3(QL)6K2G3C. All electrochemical measurements were carried out in sterile buffer and inside a Faraday cage. The impedance variation percentages (Δlog Z (%)) registered at12.12 Hz were used to show the surface change of the sensor surface at different conditions (Bayoudh et al., 2008; Mejri et al.,2010) (Eq. (1) in SI and Fig. S1). experiments using WK3(QL)6K2 and WK2(QL)6K2G3C were performed as described
above. The bare gold electrode (without peptides) incubated with102–106 CFU/mL P. aeruginosa was also tested as control. JSM- 7400F field emission scanning electron microscope (JEOL Ltd.,Tokyo, Japan) was used to characterize the gold slide surface before and after modification with sAMP and visualize the presenceof bacteria as described in the SI section.