In situ template synthesis of gold nanoparticles using a bis-imidazolium amphiphile-based hydrogel

Hypothesis: Gemini-type bis-imidazolium amphiphiles are able to stabilize gold nanoparticles (GNPs) and also form hydrogels. It should be possible to obtain GNPs synthesized within these hydrogels and stabilized by the bis-imidazolium molecules.

Experiments: Hydrogels containing a gold salt were formed using 1,3-bis[(3-octadecyl-1-imidazolio)methyl]benzene dibromide. After aging of the gel, upon addition of the reducing agent in a solvent the formation of GNPs was assessed. The gel was characterised and the GNPs were observed using High Resolution Transmission Electron Microscopy (HRTEM).

Findings: Monodisperse GNPs with an average size of ca. 5 nm and well defined icosahedral geometry were formed in situ using the bis-imidazolium amphiphile-based hydrogel as template. Furthermore the gelator is also the stabilizing ligand of the GNPs, allowing the recovery of the GNP by disassembling the gel without aggregation of the inorganic colloid.