Synthesis of solution stable end-to-end linked gold nanorod dimers via pH-dependent surface reconfiguration

Abstract

End-to-end dimers of gold nanorods are predicted to be excellent substrates for surface-enhanced spectroscopy. However, synthesis of solution-stable end-to-end dimers remains challenging. Here we exploit the pH-dependent configurational change of polyelectrolytes to initiate and terminate the gold nanorod assembly formation to produce end-to-end linked dimers at high yield. The gold nanorods are first overcoated with a polyelectrolyte and the end-to-end attachment is initiated by adding a thiol linker in acidic medium. The assembly formation is then terminated at the dimer stage by changing the pH of the medium by the addition of appropriate amount of 1,4-diazabicyclo[2.2.2]octane (DABCO).The nanorod dimers synthesized here are stable in solution for a week without any additional surface encapsulation.