Molecular quantification of density and oligomerization

Fluorescence Fluctuation Spectroscopy (FFS) is a family of techniques that takes advantage of the properties of statistical fluctuations. Thanks to the collaboration between LIPhy and the CEA team, BRM, we have been able to develop well-controlled substrates for cellular studies and, by combining FFS with photobleaching, to provide a reliable estimation of the number of molecules. In particular, we have developed a streptavidin (SAv) based platform on which various biotinylated molecules can be grafted. The SAv monolayer has been characterized by FFS but the remaining biotinylated molecules have not been quantified. We now want to go one step further by addressing more complex biomaterials for cellular studies where knowledge of the amount of molecule is fundamental. The same technique (called pbFFS for photobleaching Fluctuation Fluorescence Spectroscopy) can also be applied to oligomerization, clustering or aggregation, which mediate a myriad of biochemical processes. For example, in cell signaling, the same molecule can modulate its affinity with its partners and activate a different cellular response depending on whether it is in the monomeric or oligomeric state.