UV light-induced self-assembly of gold nanocrystals into chains and networks in a solution of silver nitrate

Controllable assemblies of nanocrystals have attracted considerable interest because they often exhibit unique collective properties that differ from those displayed by individual nanocrystals and bulk samples. Reported approaches to prepare nanocrystal assemblies based on the molecular recognitions of small molecules or biomacromolecules are effective, but often require complicated and time-consuming modification processes of nanocrystals. In this paper, we demonstrate a simple and universal approach to assemble gold nanocrystals (AuNCs) into linear chains and complex networks in aqueous silver nitrate medium under irradiation with UV light without the involvement of any modification step. Due to the strong plasmon resonance coupling verified by finite difference time domain calculation, the assembled structures of AuNCs can be used as excellent surface-enhanced Raman scattering substrates and dark-field light-scattering bioimaging probes.