Green synthesis and characterization of gold and silver nanoparticles

Abstract

Gold nanoparticles (GNPs) and silver nanoparticles (SNPs) are very attractive materials for nanotechnology, nanobiology and nanomedicine. We employ β-cyclodextrin (βCD) both as reducing and stabilizing agent for the preparation of GNPs and SNPs aqueous dispersions, to be used in biological applications. HAuCl4 and respectively AgNO3 were reduced with βCD in alkaline medium at room temperature. Reactions were monitored by measuring the intensity of the characteristic surface plasmon resonance (SPR) absorption band at 520 nm for GNPs, and at 404 nm for SNPs. The size of particles was determined from TEM images. Particularly, the average diameter of GNPs is 7.6 nm and for SNPs is 13.1 nm. The dispersions remained stable for at least a year after preparation. The nanoparticles were further characterized by AFM imaging, zeta potential and dynamic light scattering measurements, as well as by FT-Raman spectra. Their stability against acid (HCl) and saline (NaCl) solutions was also investigated.