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.