Figure 4: Antibacterial activity of Ag NWs and their particle-free supernatant to recombinant Escherichia coli. (a) Inhibition of bacterial bioluminescence by Ag NWs suspension (see also Figure 3(a)) and its supernatant (see Section 2). Mean ± standard deviation of three independent experiments is shown; (b) potential of Escherichia coli to yield colonies on agarized LB growth medium after 4-hour incubation with different nominal concentrations of Ag NWs suspension and the respective particle-free supernatant. Photo is taken after 24 h incubation of the inoculated test plates at 30°C. Opaque “spot” in (b) indicates high number of bacteria; appearance of individual colonies within the “spot” indicates decreased number of viable cells. All the Ag concentrations are nominal concentrations in Ag NWs suspension.