Potentiometric Detection of Single Nanoparticle Collision Events on a Surface Functionalized Gold Nanoelectrode

Abstract

Electrochemistry single-entity methods are of fundamental importance and show promise for ultrasensitive chemical and biological sensing applications. Recently, we have demonstrated that various nanoparticles can be detected individually based on the open circuit potential (OCP) changes induced by their collision events on a floating carbon nanoelectrode. Unlike the widely used amperometry approach, the potentiometric method provides the label-free detection of individual nanoscale entities without redox mediators in solution. However, the carbon nanoelectrode is chemically inert and limited in surface functionalization. Here, I will present our recent progress of using surface functionalized gold nanoelectrode (GNE) to replace the carbon nanoelectrode for potentiometric single-entity studies. By utilizing the advantage of mixed surface functionalization of GNE with the Raman reporter molecule and polyethylene glycol or zwitterionic molecules, we formed near ‘stealth’ GNE surface and demonstrated that the non-specific adsorptions of nanoparticles to the GNE surface can be minimized, allowing continuous hit-n-run events for over 30 minutes. The surface functionalized GNE also enabled surface enhanced Raman spectroscopy (SERS) measurements. By using simultaneous time-resolved OCP and SERS measurements, both the OCP and SERS signals induced by the hit-n-run type of collision events can be better understood.