Synthesis of a gold nanoparticle dimer plasmonic resonator through two-phase-mediated functionalization.

We report that Au nanoparticles, ligand-exchanged with a thiol ligand at the liquid-liquid interface, were dimerized using an N,N'-diisopropylcarbodiimide-mediated amide bond formation. This dimerization of 60 nm sized Au nanoparticles achieved 24% overall yield and was visually confirmed by transmission electron microscopy as well as by scanning electron microscopy images. The resultant electromagnetic field enhancement of a single Au nanoparticle dimer was proven by dark field spectroscopy which, in turn, made the Au nanoparticle dimer suitable for molecular sensing applications, such as in surface enhanced Raman spectroscopy. Our dimerization method demonstrated that the synthesis of Au nanoparticle dimers with a high yield and enhanced optical properties of the dimers were possible. Our methodology also has good prospects as regards the formation of nanoscale building blocks.