Two-step size- and shape-separation of biosynthesized gold nanoparticles

► Green synthesis of gold nanoparticles by the extract of Cacumen Platycladi leaf. ► Size separation of nanoparticles was achieved by density-gradients centrifugation. ► Shape separation of nanoparticles was achieved by agrose gel electrophoresis. ► Monodisperse nanoparticles with uniform morphology were obtained via separation.