The Impact of Bacteria Exposure on the Plasmonic Response of Silver\n Nanostructured Surfaces

Abstract

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