Facile control of the self-assembly of gold nanoparticles by changing the capping agent structures

Facile synthesis and 1D self-assembly of gold nanoparticles were achieved using a series of nonionic surfactants (Tween 20, Tween 40, and Tween 60). The assembly process can be controlled by adjusting the fine structures of surfactants. The effects of the molecular structures of capping agents were demonstrated and the formation mechanism based on the nonuniform distribution of capping ligands around gold nanoparticles was proposed. Systems with mixed capping agents (Tween 20 and Tween 60 or Triton X-100) were also investigated. Due to the different capping fashions of the mixed surfactants, the obtained gold nanostructures were changed from chains to particles. Besides, the diverse capping fashions can also interpret the different stabilities of the nanostructures in the saline solutions.