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.
Bibliographical noteFunding Information:
All authors wish to thank Dr. José Yacamán for the facilities provided in the characterization of the systems by electronic microscopy, as well as to the Kleberg Advanced Microscopy Center of the University of Texas at San Antonio Physics and Astronomy and the Laboratory of Biomaterials of Physics Department, University of Sonora. The authors are also grateful for the support of the SAGARPA Projects 17-PFA-IIDTTT-001448-L000-DF, as well as the support provided by the Secretariat of Public Education (SEP) through PRODEP (Programa para el Desarrollo Profesional Docente) by the Postdoc fellowship 0511-6/17-4022 and AMH would like to thank Conacyt for Post-Doctoral Fellowship (2019-000019-01NACV-00449), Support Number 740180. All authors wish to thank the graduate program in nanotechnology at the University of Sonora for DLS, Zeta-sizer, characterizations support. JMAVN would like to thank Conacyt for Fellowship Number 748633. This publication was supported by the University of Sonora and the Professional Development Program (PRODEP) by SEP-México.
© 2021, The Author(s).
- Au@Ag core@shell nanoparticles
- Gompertz model
- Lag phase
- Rumex hymenosepalus