Background & motivation

Background and motivation

In the biomedical field, fluorescence is the by far most widely used modality for cellular imaging, offering a unique combination of spatial and temporal resolution, sensitivity and specificity. There has been a remarkable development of fluorescence-based super-resolution microscopy techniques in the last decade. "Super-resolution" means that the resolution of the imaging is not limited by the wavelength of the light used to image a sample, and the main scientists behind this development were awarded the Nobel Prize in 2014.

By the development of fluorescence-based super-resolution microscopy it has become possible to image cellular proteins marked with fluorescence emitters (fluorophores), with a ten-fold higher resolution than with any other fluorescence microscopy technique. In a previous EU FP7 project ( ), this was used to analyze how certain proteins were spatially distributed in breast and prostate cancer cells, compared to in corresponding non-cancer cells, and was demonstrated as a new basis for cancer diagnosis. Two of the NanoVIB partners (KTH and KI) have also more recently applied super-resolution microscopy to study bacterial surface proteins of Streptococcus Pneumoniae (pneumococci). Pneumococcal infections represent a major cause of morbidity and mortality world-wide. These super-resolution microscopy studies could shed new light on how specific surface proteins of these bacteria are spatially distributed on the cells, and provided important evidence that the virulence (capacity to generate disease) and invasiveness of these bacteria is strongly coupled to such spatial protein distribution patterns (Figure 1). Clearly, imaging of these patterns with yet higher spatial resolution can lead to a significantly increased understanding of the mechanisms underlying pneumococcal virulence and invasiveness.