Fig. 1.
Characterization of composite and exhibits of its unique antimicrobial activity. (A) Transmission electron micrograph of Ag-BM. The composite matrix appears as nanosheets of 3- to 4-nm thickness and the embedded nanoparticles are seen as dots. Some sheets and particles are indicated by circles. The matrix made of the boehmite–chitosan acts like a cage in which the nanoparticles are trapped. The particle sizes are much smaller than those of a typical aqueous phase synthesis. Inset shows an expanded view of one particle. (B) Bacterial load measured in water as a function of batch upon spiking 105 CFU/mL of E. coli. Red bars indicate the point of reactivation. (C) Silver ion concentration measured by ICP-MS (blue trace) and corresponding bacterial count in CFU/mL for one of the cycles (number of trials: 40th–140th) (red trace) from batch measurements. (D) X-ray photoemission spectra of initial (red trace), saturated (blue trace), and reactivated (pink trace) composites in the Ag 3d region and the Ca 2p region (Inset). The intensity of Ca 2p (Inset) is weak as the coating is thin. The reactivated composite shows an increased Ag 3d intensity due to removal of scale-forming species and better exposure of the nanoparticle surface.