Au@Ag Core@Shell Nanoparticles Synthesized with Rumex hymenosepalus as Antimicrobial Agent

Abstract

In this work, we used a sequential method of synthesis for gold–silver bimetallic nanoparticles with core@shell structure (Au@AgNPs). Rumex hymenosepalus root extract (Rh), which presents high content in catechins and stilbenes, was used as reductor agent in nanoparticles synthesis. Size distribution obtained by Transmission Electron Microscopy (TEM) gives a mean diameter of 36 ± 11 nm for Au@AgNPs, 24 ± 4 nm for gold nanoparticles (AuNPs), and 13 ± 3 nm for silver nanoparticles (AgNPs). The geometrical shapes of NPs were principally quasi-spherical. The thickness of the silver shell over AuNPs is around 6 nm and covered by active biomolecules onto the surface. Nanoparticles characterization included high angle annular dark field images (HAADF) recorded with a scanning transmission electron microscope (STEM), Energy-Dispersive X-ray Spectroscopy (EDS), X-Ray Diffraction (XRD), UV–Vis Spectroscopy, Zeta Potential, and Dynamic Light Scattering (DLS). Fourier Transform Infrared Spectrometer (FTIR), and X-ray Photoelectron Spectroscopy (XPS) show that nanoparticles are stabilized by extract molecules. A growth kinetics study was performed using the Gompertz model for microorganisms exposed to nanomaterials. The results indicate that AgNPs and Au@AgNPs affect the lag phase and growth rate of Escherichia coli and Candida albicans in a dose-dependent manner, with a better response for Au@AgNPs

New formula of the green synthesised Au@Ag core@shell nanoparticles using propolis extract presented high antibacterial and anticancer activity

“…Here, SPR was perceptible in the peak produced by the nanoparticle between 533 and 555 nm, confirming the nanoform’s presence. Furthermore, the resulted data have a longer wavelength than the previously reported Au@AgNPs (Villalobos-Noriega et al 2021 ), which can be explained by the high gold content in the sample (Loiseau et al 2019 ). Thus, we are investigating the other varied properties due to the high concentration of HAuCl 4 in the core@shell formula compared to the previously reported data.…”

“…Gold-silver bimetallic nanoparticles (Au-AgNPs) have demonstrated a synergistic activity, generating bifunctional effects compared to their monometallic counterparts. The primary benefits of Au@AgNPs are biocompatibility, reduced silver nanoparticles (AgNPs) toxicity toward healthy human cells and significant antibacterial activity (Deng et al 2021 ; Villalobos-Noriega et al 2021 ; Rabiee et al 2022 ).…”

Detection of Organophosphorus Pesticides Using Silver-Coated Gold Nanoparticles

“…34,35 High-resolution TEM images (inset of Figure 3A) show the (111) lattice spacing (0.213 nm) and (220) lattice spacing (0.169 nm) of crystalline Ag. 36 EDS data (Figure 3B) and elemental mapping (Figure 3C) indicate the existence of both Au and Ag elements for the Au@Ag NPs. XPS measurement was further carried out, and the binding energy peaks of Au and Ag were found (Figure 3D).…”

“…The Au@Ag NPs were further characterized by high-resolution TEM, EDS, XPS, and XRD. As shown in Figure A, a core–shell nanostructure image can be captured for the Au@Ag NPs, although it is not easy to distinguish Au and Ag for TEM imaging. , High-resolution TEM images (inset of Figure A) show the (111) lattice spacing (0.213 nm) and (220) lattice spacing (0.169 nm) of crystalline Ag . EDS data (Figure B) and elemental mapping (Figure C) indicate the existence of both Au and Ag elements for the Au@Ag NPs.…”

Bimetallic Au–Ag Nanoparticles: Advanced Nanotechnology for Tackling Antimicrobial Resistance

“…The growth kinetics of microorganisms was analyzed by the Gompertz model. The findings suggested that silver NPs and bimetallic Au–Ag NPs had a dose-dependent effect on the lag phase and growth rate of E. coli and Candida albicans , with the Au–Ag NPs having a better response [ 120 , 124 ].…”