The morphology of AuNPs was characterized by using a JEOL TEM 1210 transmission electron microscope at 120 kV accelerating voltage. The samples were prepared by drop casting small amounts of the nanoparticle colloid on copper grids. X-ray powder diffraction patterns were recorded on a Bruker D8 Discover equipped with a LynxEye detector, using CuKα radiation (λ = 1.5405 Å, nickel filter). The zeta potential was measured by using a Malvern Zetasizer Nanoseries, Nano-ZS90.