Tracking Interfacial Dynamics of a Single Nanoparticle Using Plasmonic Scattering Interferometry.

The ability to track interfacial dynamics of a single nanoparticle at the solution-solid interface is crucial for understanding physical, chemical, and biological processes, but it remains a challenge. Here, we demonstrated a plasmonic imaging technique that can track unlabeled nanoparticles at the solution-solid interface with high spatial and temporal resolutions. This technique is based on particle-induced interferometric scattering of a surface plasmonic wave, which results in a high vertical sensitivity. Using this ability, we tracked the trajectories of a single nanoparticle interacting with a surface, measured the hydrodynamically hindered diffusion of nanoparticles, and revealed the surface chemistry-dependent behavior of nanoparticles at the interface. The application for tracking formation of membranes from a lipid vesicle was demonstrated, indicating the potential for investigating a broad range of nano-objects at interfaces in a complex environment.