Polyamine ligand-mediated self-assembly of gold and silver nanoparticles into chainlike structures in aqueous solution: towards new nanostructured chemosensors.

Polyamine ligands are very versatile compounds due to their water solubility and flexibility. In the present work, we have exploited the binding ability of a polyamine molecular linker (L (2-)) bearing different functional groups, which favors the self-assembling of silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) into 1D nanochains in aqueous solution. The chainlike assemblies of AuNPs and AgNPs were structurally stable for a long period of time, during which their characteristic optical properties remained unchanged. The mechanism of AuNPs and AgNPs chain assembly associated with the induction of electric dipole-dipole interactions arising from the partial ligand exchange of surface-adsorbed citrate ions by (L (2-)) was investigated. UV/Vis spectrophotometry and transmission electron microscopy (TEM) were used to determine timedependent structural changes associated with formation of the 1D nanoparticle structures. Finally, the sensing of Hg(2+) in aqueous solution using AgNPs@(L)(2-) and AuNPs@(L)(2-) assemblies was also carried out in aqueous solution.