Fig. 3: ESM identification of single proteins using antibodies.

a Schematic showing the behaviors of single IgA, Tg, and IgM proteins on the anti-IgA modified surface. b ESM images showing binding of IgA to anti-IgA immobilized on the surface, and negative control experiment, exposing of IgM to anti-IgA surface. c Kinetics of 20 nM IgA binding to anti-IgA determined by digital counting of the binding/unbinding of single IgA molecules (black curve and solid red fitted curve), and negative control experiments exposing of Tg and IgM to anti-IgA surface. Inset are zoom-in view of the control experiment results. d Image intensity histogram obtained from association, and dissociation processes of 20 nM IgA injected onto anti-IgA modified surface, where the solid lines are Gaussian fitting. e Extracting mean radial profiles from one differential frame where one protein has been recognized to construct full-circle point spread function (PSF). f Correcting the ESM image distortions by cross-correlating the ESM images with the full-circle PSF. g Tracking the position of one protein binding on the sensor surface with an effective frame rate of 50 fps after average and duration of 0.5 s using TrackMate. STD represents the standard deviation. h Localization standard deviations (STD) histograms achieved by tracking different molecules. i Super-resolution image, showing the localized positions of the cumulative IgA binding events on anti-IgA immobilized on the surface. j Super-resolution image, showing the localized positions of the Tg and IgM hitting events on anti-IgA immobilized on the anti-IgA immobilized on the surface. Incident wavelength: 450 nm. Incident light intensity and camera exposure time are 20 kW cm^-2 and 10 ms. The image intensity was normalized with an incident light intensity of 60 kW cm⁻² and a camera exposure time of 5 ms. The experiments were repeated three times with similar results for b and i.