Interferometric scattering microscopy (iSCAT) is an extremely sensitive imaging method based on the efficient detection of light scattered by nanoscopic objects. The ability to, at least in principle, maintain high imaging contrast independent of exposure time or scattering cross section of the object imaged allows for unique applications in single-particle tracking, label-free imaging of nanoscopic (dis)assembly, and quantitative single-molecule characterization.We illustrate these capabilities in areas as diverse as mechanistic studies of motor protein function, viral capsid assembly, and single-molecule mass measurement in solution. We anticipate that iSCAT will become a widely used approach to unravel previously hidden details of biomolecular dynamics and interactions. Expected final online publication date for the Annual Review of Physical Chemistry Volume 70 is April 20, 2019. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
