Fabrication of gold nanoparticles with different morphologies in HEPES buffer

Abstract

Gold nanoparticles with different morphologies, such as spindle, octahedron, and decahedron were obtained by using different molar ratios of HAuCl 4 /HEPES in the presence and absence of surfactants at room temperature. These nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), scanning electron microcopy (SEM), energy-dispersive X-rays analysis (EDX), and selected area electron diffraction (SAED). The kinetics of the formation of gold nanoparticles in HEPES buffer was studied by UV-visible spectrophotometer. The formation of gold nanoparticles was strongly dependent on the concentration of HEPES and pH value. The surfactants play a crucial role in the size and shape controlled synthesis of gold nanoparticles.

Engineering filamentous bacteriophages for enhanced gold binding and metallization properties

“…6) implying that HEPES buffer is especially acting on HAuCl 4 . It has been previously demonstrated that nitrogen-centered cationic free radicals can be exposed by HEPES buffer in the presence of Au (III) ions, forming AuNPs without any need of reducing agents [36]. Similarly, we observed Au cluster formation for our control samples as well without any phages (Fig.…”

Green synthesis of gold nanoparticles using plant extracts as reducing agents

“…This variety of geometrical shapes is typical of GNPs and has been described in the literature. [30][31][32][33][34] Several TEM images are presented in Figure 8 as examples of the GNP shapes formed when the different plant extracts were used. In some cases, these shapes corresponded to single crystals, as can be deduced from their diffraction patterns, eg, Figure 8, B and C. Since the TEM images show only a few particles in each picture, statistically reliable distributions of these shapes and sizes cannot be evaluated.…”

Positively charged, surfactant-free gold nanoparticles for nucleic acid delivery

“…22 In addition, Au nanostructures with shapes ranging from 3D octahedra, triangles, to 2D hexagonal nanoplates have been obtained through changes in the CTAB concentration, used as both a reducing agent and capping ligand during hydrothermal treatment of chloroauric acid. 21,29,30 In addition, many studies have shown that the biological uptake of positively charged nanoparticles is higher than their negatively charged counterparts, but with positively charged Au nanoparticles produced from CTAB showing a high level of biological toxicity. [24][25][26][27][28] The presence of surfactants during the formation of Au nanoparticles may affect their final size and their shape diversity; this is due to specific adsorption of Au-surfactant complexes on the facets of the nanoparticle seeds that limit their growth and enhance their anisotropic shape.…”