SEM images of the gold surface functionalized with the four sAMPs show significantly higher numbers of P. aeruginosa obtained with the active cysteine modified WK3(QL)6K2G3C peptide as compared to the corresponding control peptides, WK3(QL)6K2,
WK2(QL)6K2 and CE2(QL)6E2 (Fig. S3). Additionally, a sensor modified
with a different control peptide lacking both cysteine and
antimicrobial activity, CE2(QL)6E2 showed no impedance change
upon exposure to bacteria (Fig. S4). The binding of bacteria to bare
gold was negligible. These results demonstrate that both the cysteine
residue and the antimicrobial activity are essential features of
the engineered sAMPs for providing sufficient binding and detection
sensitivity for impedimetric detection of bacterial pathogens.