Green synthesis of silver and gold nanoparticles using Zingiber officinale root extract and antibacterial activity of silver nanoparticles against food pathogens

In the present study, we synthesized silver and gold nanoparticles with a particle size of 10–20 nm, using Zingiber officinale root extract as a reducing and capping agent. Chloroauric acid (HAuCl₄) and silver nitrate (AgNO₃) were mixed with Z. officinale root extract for the production of silver (AgNPs) and gold nanoparticles (AuNPs). The surface plasmon absorbance spectra of AgNPs and AuNPs were observed at 436–531 nm, respectively. Optimum nanoparticle production was achieved at pH 8 and 9, 1 mM metal ion, a reaction temperature 50 °C and reaction time of 150–180 min for AgNPs and AuNPs, respectively. An energy-dispersive X-ray spectroscopy (SEM–EDS) study provides proof for the purity of AgNPs and AuNPs. Transmission electron microscopy images show the diameter of well-dispersed AgNPs (10–20 nm) and AuNPs (5–20 nm). The nanocrystalline phase of Ag and Au with FCC crystal structures have been confirmed by X-ray diffraction analysis. Fourier transform infrared spectroscopy analysis shows the respective peaks for the potential biomolecules in the ginger rhizome extract, which are responsible for the reduction in metal ions and synthesized AgNPs and AuNPs. In addition, the synthesized AgNPs showed a moderate antibacterial activity against bacterial food pathogens.