Enhanced antimicrobial activity with faceted silver nanostructures

Faceted silver nanostructures including triangular nanoprisms, nanotetrahedra, and nanodecahedra were synthesized via a facile photochemical method at controlled wavelengths using spherical nanoparticles as the seeds. Scanning transmission electron microscopy studies showed that the resulting nanostructures were much larger in size (20–50 nm) than the spherical seed nanoparticles (under 5 nm), and X-ray diffraction as well as high-resolution transmission electron microscopy measurements confirmed that these nanostructures exhibited predominantly {111} faceted surfaces. Importantly, the silver nanostructures demonstrated markedly better antimicrobial activity than the spherical seed nanoparticles as evidenced by a lower minimum inhibitory concentration and more dramatic changes in both growth rate and lag phase at lower concentrations, which were attributed to the greater reactivity of the {111} faceted surfaces toward oxygen-rich bacterial surface moieties that allowed for more rapid localization to bacterial cells and increased interactions with structurally vital outer-membrane proteins. These results highlight the significance of surface morphologies of metal nanostructures in the manipulation of their antimicrobial activity.