Ion-induced fluorescence imaging of endosomes

Imaging laboratories at Jyväskylä and Singapore are collaborating on the development of fluorescence imaging of cytoplasmic endosomes using a combination of proton induced fluorescence (PIF) with direct Scanning Transmission Ion Microscopy (direct-STIM) for sub-cellular structural imaging. A549 lung carcinoma cells were cultivated and stained for epidermal growth factor receptor (EGFR) and receptor α2β1 integrin. In this paper, we demonstrate that cells can be imaged at sub-150 nm resolution using the PIF technique. In addition, the same target cell was imaged at 50 and 25 nm resolution by using proton and He-STIM, respectively. The combination of both techniques offer a powerful tool to improve fluorescence imaging beyond optical diffraction limits.