to discriminate between live and dead bacteria. Since the mechanism
of antimicrobial activity of AMPs involves disruption of
the bacterial cell envelope (Hartmann et al., 2010), we sought to
investigate whether different binding of sAMPs to live/dead cell
membranes can be used to differentiate between dead and live
cells. Fig. 5 shows the impedimetric responses of the sAMP biosensor
to the four bacteria in live and dead conditions. Bacteria
grown to mid-log phase were used as live bacteria sample. Dead
bacteria samples were prepared by incubating bacterial culture
grown to mid-log phase at 100 °C for 1 h. The sensor shows significantly
different responses to live and dead bacteria. Exposure
to dead bacteria resulted in lower Δlog Z (%) for all four bacteria
species, as compared to sensors exposed to live bacteria. The results
indicate a different recognition behavior of the dead bacteria
for the immobilized sAMP layer. This phenomenon indicates that
the sAMP impedimetric biosensor is not only able to detect bacteria
but also to differentiate dead bacteria from live ones.