Fig. 5: 3D tracking of clathrin-coated pits and SARS-CoV-2 on the plasma membrane of a live cell.

a Exemplary raw C-iSCAT image of the periphery of a COS-7 cell showing vesicles, ER network and MTs. Scale bar is 2 μm in a–c. b Overlay of single particle trajectories of vesicles detected and tracked in a. Color map encodes the absolute value of the contrast change normalized for each trajectory. c Overlay of a with CF of clathrin labeled with mCerulean3 (cyan). d Close-up of c including clathrin-coated pits. Time course over 75 s shows contrast inversion of a clathrin-coated pit indicated with a white arrow. Scale bar is 500 nm. e Extracted 3D trajectory of the clathrin-coated pit marked in d. Color map encodes the temporal evolution starting from t = 0 s (magenta) to t = 75 s (cyan). CF (f) and C-iSCAT (g) images of a single SARS-CoV-2 particle on a bare cover glass. Scale bar is 200 nm. h Merge of the C-iSCAT and CF (cyan) signals of labeled SARS-CoV-2 particles on the plasma membrane at the periphery of a COS-7 cell. Scale bar is 1 μm. i Color-coded data show a highly dense 2D trajectory of a diffusing SARS-CoV-2 particle obtained in W-iSCAT from the field of view indicated by the white dashed square in f. The star symbols represent the trajectory of the same event recorded simultaneously in the CF channel. Scale bar is 250 nm. j Extracted height displacement of the SARS-CoV-2 particle over time obtained from W-iSCAT images. k 3D representation of the trajectory depicted in i. Colors in i and k follow the same map as in j and encode time over the course of 65 s at a frame rate of 1 kHz.