The antibacterial features of silver NP modified wool fabrics
were evaluated against the Gram negative bacteria, E. coli. Fig. 6
shows that three batches of wool fabrics treated with silver NPs
(nanoprism I, nanodisks I and II) exhibited significant antibacterial
ability. As can be seen, there are far more colonies of viable bacteria
corresponding to the untreated wool fabrics (Fig. 6d) than the modified
wool fabrics (Fig. 6a–c). However, the antibacterial activities
differed slightly for the wool fabrics treated with silver NPs of different
morphologies. Reduction of CFU was calculated to describe
the antibacterial efficiency of treated samples. The reduction of
CFU was 76.92%, 98.46% and 93.84% for wool fabrics treated with
nanoprism I, nanodisks I and II, respectively. The antimicrobial
mechanism of silver NPs has been discussed in many literatures
[64–67]. It has been suggested that the silver NPs interact with
the bacterial membranes to cause structural changes and degradation
of cells [64]. The silver NPs could break permeability of outer
membrane, inhibit respiration and growth of cells, and destroy
the structure of membrane, resulting in cell decomposition and
death eventually [65]. The anisotropic silver NPs possess a relatively
large surface area, which may also benefit the antibacterial
action.