High-Speed Single Particle Tracking on Model Lipid Membranes

Abstract

Interferometric scattering detection microscopy (iSCAT) is a powerful method for single particle tracking (SPT) experiments. Recently, we reported on the use of iSCAT for visualizing the diffusion of gold nanoparticles (GNPs) as small as 5nm attached to lipids in model membranes with nanometer lateral precision and at up to 1 MHz frame rate. Exploiting this high spatial and temporal resolution, we revealed transient nanoscopic confinements of nanometer size on millisecond time scales on supported lipid bilayers (SLBs) [1]. To avoid artifacts caused by the glass-lipid interface, we have extended our studies to giant unilamellar vesicles (GUVs). Here, we demonstrate one of the unique capabilities of iSCAT, namely high axial resolution in tracking the displacement of a nanoparticle. We present three-dimensional trajectories of GNP-labeled lipids and unlabeled virus-like particles diffusing on a GUV membrane [2].[1] C.-L. Hsieh, S. Spindler, J. Ehrig, V. Sandoghdar, J. Phys. Chem. B 118 (2014).[2] S. Spindler, H. Stein, J. Ehrig, V. Sandoghdar, in preparation.