Macrocyclic imidazolium-based amphiphiles for the synthesis of gold nanoparticles and delivery of anionic drugs.

In the present work, we have explored the use of amphiphilic bis-imidazolium based macrocycles and an open chain analog for the successful synthesis of gold nanoparticles (AuNPs). The macrocyclic ligands incorporate hydrophobic chains of different lengths, and the newly synthesized ligands were further used for the synthesis of AuNPs in a biphasic system. The successfully synthesized AuNPs were thoroughly characterized. The sizes of the AuNPs were ca. 8 nm, using macrocyclic ligands bearing two 10 carbon atoms alkyl chains, ca. 5 nm in the case of macrocyclic ligands with two 18 carbon atoms alkyl chains, and ca. 7 nm for the open chain ligand with two 18 carbon atoms alkyl chains. Their possible application as vehicles to load and release anionic drugs (such as sodium ibuprofenate) was also assessed and compared with previously described open chain analogs. In this case, it was observed that the AuNPs had high efficiency in extracting sodium ibuprofenate from an aqueous solution. The application as a drug delivery vehicle was confirmed by in vitro release experiments at different pH values.