Figure 1. Setup and principle of plasmonic scattering microscopy (PSM).

(a) Simplified sketch of the optical setup, where surface plasmonic waves (E_p) are excited by light from the bottom of a gold-coated glass slide and scattering of the plasmonic waves by a particle or protein (E_s) and by the gold surface (E_b) is collected from the top to form a PSM image. (b) Raw time sequence of PSM images of 26 nm polystyrene nanoparticles (left), and background and drift corrected PSM image (right). A detailed description of the setup and imaging processing can be found in Supplementary Figure 1, Supplementary Note 4 and Supplementary Note 7. The experiment is repeated by 5 times with similar results.