Imaging Bactericidal Effect of Faceted Ag Nanostructures (FAgN) on Gram Negative, Coli Form Escherichia coli Bacteria

Abstract

The present work highlights transmission electron microscopy (TEM) imaging study of the faceted Ag nanoparticle-led bactericidal activity in gram negative Escherichia coli. The faceted nanostructures were derived from a low temperature reaction precursor with silver nitrate (AgNO3) and tri-sodium citrate (Na3C6H5O7) as the main reactants and sodium borohydride (NaBH4) as reductant. Formation of polyhedral type-faceted nanostructures of typical dimension 20–30 nm was evident from the electron microscopy studies. As revealed from optical studies, the bacterial growth is substantially hindered upon treatment with faceted Ag nanostructured (FAgN) systems. Moreover, a strong bactericidal attack of FAgN (concentration ∼20 × 10–4 mg/mL) on E. coli was evident from apparently visible de-skinned area of the bacterium species. While in most of the bacteria specimens, the de-skinned area of the cytoskeletal membrane is in the range of 10–20% of the total area, in a few cases, it is as high as 58%. The unaffected parts, which remained intact can be considered as non-targeted sites. Understanding the role of edges and facets of nanoscale Ag on bacterial inhibition and cidal activity would provide new insights for remedial measures in biomedical and bioengineering applications.