Fig. 5

3D sub-diffraction uSEE microscopy imaging in neuronal cells. A confocally imaged 3D z-stack of a cell incubated with colominic acid functionalized UCNPs (a-c). a WGA-Alexa Fluor 647, highlighting the cell plasma membrane. b Confocal images of the UCNPs inside the cell taken at excitation power density corresponding to the lateral diffraction limit (11.8 mW μm⁻²). c Confocal images of the UCNPs inside the cell taken at low powers (1.7 mW μm⁻²), corresponding to sub-diffraction uSEE microscopy. Corresponding axial and lateral cross sections through the 3D z-stacks are shown in (d–f). The gray lines indicate the position of the mutually perpendicular cross sections. The dashed white line frames the cell membrane and the dotted white line highlights the nuclei. Closed in zoom on particles inside the cell (orange-dashed volume in (e, f)) confirms a resolution twice better than the diffraction limit both in axial (g) and lateral (h) directions