  Silver, especially in the form of nanostructures, is widely employed as an
antimicrobial agent in a large range of commercial products. The origin of the
biocidal mechanism has been elucidated in the last decades, and most likely
originates from silver cation release due to oxidative dissolution followed by
cellular uptake of silver ions, a process that causes a severe disruption of
bacterial metabolism and eventually leads to eradication. Despite the large
number of works dealing with the effects of nanosilver shape/size on the
antibacterial mechanism and on the (bio)physical chemistry pathways that drive
bacterial eradication, little effort has been devoted to the investigation of
the silver NPs plasmon response upon interaction with bacteria. Here we present
a detailed investigation of the bacteria-induced changes of the plasmon
spectral and dynamical features after exposure to one of the most studied
bacterial models, Escherichia Coli. Ultrafast pump-probe measurements indicate
that the dramatic changes on particle size/shape and crystallinity, which stem
from a bacteria-induced oxidative dissolution process, translate into a clear
modification of the plasmon spectral and dynamical features. This study may
open innovative new avenues in the field of biophysics of bio-responsive
materials, with the aim of providing new and reliable biophysical signatures of
the interaction of these materials with complex biological environments.
