Synthesis of Gold Nanotadpoles by a Temperature-Reducing Seed Approach and the Dielectrophoretic Manipulation

Tadpole-shaped gold nanoparticles are synthesized in high yield by a simple temperature-reducing seeding approach, without additional capping agent or surfactant. The initial concentration of gold ions, the added seed colloids, and the solution reaction temperature play critical roles. Examination of nanoparticles at different stages of the reaction with transmission electron microscopy and UV−vis spectrophotometry reveal the formation of the special structure as a kind of aggregation-based growth, including spherical aggregation at the boiling temperature and linear aggregation at the reduced temperature. The latter is further studied using a theoretical model. Moreover, thanks to the asymmetric structure of gold nanotadpoles, three types of chaining of gold nanotadpoles are experimentally obtained in nonuniform alternating-current electric fields at different frequencies by dielectrophoresis, which are in qualitative agreement with the simulation results.