Biophysical Imaging

Fluorescence microscopy is a powerful tool in many life science research areas; thanks to its live-cell compatibility and its ability to observe only specifically labeled molecules of interest. However, in the field of virology, this technique has traditionally been of limited use, specifically due to the fundamental resolution limit associated with the diffraction of the visible light. The diffraction limit makes fluorescence microscopes unable to resolve details below approximately 200 nm in the focal plane and approximately 600 nm along the optical axis, thus making studies of approximately 100-nm-sized virus particles infeasible. Therefore, for a long time, virus visualization was performed solely via electron microscopy-based methods, which – with its subnanometre resolution – enabled for numerous insights into details of virus structures. On the other hand, electron microscopy-based methods require laborious preparation of biological sample (fixation or freezing) making them unsuitable for the study of dynamic processes of viruses and virus–cell interactions.