Photon-Induced Near-Field Electron Microscopy of Eukaryotic Cells

Photon-induced near-field electron microscopy (PINEM) is a technique to produce and then image evanescent electromagnetic fields on the surfaces of nanostructures. Most previous applications of PINEM have imaged surface plasmon-polariton waves on conducting nanomaterials. Here, the application of PINEM on whole human cancer cells and membrane vesicles isolated from them is reported. We show that photons induce time-, orientation-, and polarization-dependent evanescent fields on the surfaces of A431 cancer cells and isolated membrane vesicles. Furthermore, the addition of a ligand to the major surface receptor on these cells and vesicles (epidermal growth factor receptor, EGFR) reduces the intensity of these fields in both preparations. We propose that in the absence of plasmon waves in biological samples, these evanescent fields reflect the changes in EGFR kinase domain polarization upon ligand binding.