Enhancing the resolution of STED microscopy by SPLIT and flimGANE

Stimulated emission depletion (STED) microscopy is a powerful super-resolution microscopy technique that enables observation of sub-cellular structures with spatial resolution well below the diffraction limit. The higher the STED beam intensity, the higher the resolution, but at the cost of increased photo-damage, which significantly limits the application of STED microscopy in live specimens. The separation by lifetime tuning (SPLIT) technique uses a time-resolved acquisition and a phasor-based analysis to efficiently distinguish photons emitted from the center and from the periphery of the effective fluorescent region, thus improves the resolution of STED microscopy without increasing the STED beam intensity. Furthermore, the SPLIT method is combined with a deep learning-based phasor analysis algorithm termed flimGANE (fluorescence lifetime imaging based on a generative adversarial network), to improve the robustness of SPLIT-STED allowing improving the resolution up to 1.45 folds at the half of the depletion laser beam intensity.