Letter pubs.acs.org/NanoLett
Label-Free, All-Optical Detection, Imaging, and Tracking of a Single Protein J. Ortega Arroyo,† J. Andrecka,† K. M. Spillane,† N. Billington,‡ Y. Takagi,‡ J. R. Sellers,‡ and P. Kukura*,† †
Physical and Theoretical Chemistry Laboratory, South Parks Road, Oxford OX1 3QZ, United Kingdom Laboratory of Molecular Physiology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, United States
‡
S Supporting Information *
ABSTRACT: Optical detection of individual proteins requires fluorescent labeling. Cavity and plasmonic methodologies enhance single molecule signatures in the absence of any labels but have struggled to demonstrate routine and quantitative single protein detection. Here, we used interferometric scattering microscopy not only to detect but also to image and nanometrically track the motion of single myosin 5a heavy meromyosin molecules without the use of labels or any nanoscopic amplification. Together with the simple experimental arrangement, an intrinsic independence from strong electronic transition dipoles and a detection limit of
