Combined Topography, Recognition, and Fluorescence Measurements on Cells
Conventional optical microscopy techniques, such as bright eld, cross-polarized light, phase contrast, dark eld, and differential interference contrast provide morphological and structural information of cells and cellular organelles, while uorescence microscopy allows for imaging specic molecular components and for determining the localization of molecules in cells down to the single-molecule level,1 making it possible to follow cellular processes and to monitor the dynamics of living cell components. The lateral and axial resolution of conventional optical microscopy is limited by diffraction, which is typically approximately 200-300 nm. Recently, optical super-resolution techniques have been developed, such as single-molecule optical microscopy,2 saturated structured illumination microscopy,3 stimulated emission depletion microscopy,4 photoactivation localization microscopy,5,6 and stochastic optical reconstruction microscopy,7 which surpass the diffraction limit by applying concepts such as point-spread-function engineering or by utilizing the high accuracy of single-molecule localization. Thereby, a lateral resolution of 20-50 nm can be achieved and super-resolution in 3D is also feasible.