Sensing Amyloid-β Aggregation Using Luminescent Dipyridophenazine Ruthenium(II) Complexes

The aggregation of amyloid-beta (A beta) peptides has been associated with the onset of Alzheimer's disease. Here, we report the use of a luminescent dipyridophenazine ruthenium(II) complex to monitor A beta fibrillization. This complex is not photoluminescent in aqueous solution nor in the presence of monomeric A beta, but it presents a strong photoluminescence in the presence of A beta fibril aggregates. One of the advantages of this metal complex is its large Stokes shift (180 nm). Furthermore, the long-lived photoluminescence lifetime of this ruthenium complex allows its use for the detection of fibrillar proteins in the presence of short-lived fluorescent backgrounds, using time-gating technology. We will present evidence of the advantages of dipyridophenazine ruthenium (II) complexes for monitoring protein fibrillization in highly fluorescent media.