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In this study, the antibacterial effect of novel copper (Cu) and silver (Ag) metal-based coreshell nanostructures against Escherichia coli (E. coli-Gram negative) was investigated. The novel copper-and silver-based nanostructures were prepared separately by using nontoxic, biodegradable, and biocompatible biopolymers chitosan and guar gumpolyvinyl alcohol (GG-PVA), which were modified by inorganic phases SiO2 and sepiolite. On the other hand, guar gum-PVA (GG-PVA) was modified by sepiolite, and this nanostructure was prepared only for silver. Besides, Cu was dispersed in a different biopolymer chitosan by sonochemical method in the presence and absence of SiO2. X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and X-ray diffraction (XRD) techniques were used to characterize the surface chemistry and morphology of the core/shell nanostructure. Nanoscale zero-valent Cu (NZVCu) was found under thin CuO film according to the XPS results. SEM images showed that spherical Cu/CuO@ SiO2 nanostructures (100 nm) were homogenously dispersed in the chitosan by using sonochemical method. Antibacterial property of the core-shell nanostructures was analyzed by well-diffusion method against Escherichia coli (E. coli-Gram negative). Cu/CuO@ SiO2 nanostructures were found very effective against the E. coli due to high ratio of NZVCu in the nanostructure.