Fabrication of gold nanoparticles with different morphologies in HEPES buffer

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.