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

Abstract

The aggregation of amyloid-β (Aβ) 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 Aβ fibrillization. This complex is not photoluminescent in aqueous solution nor in the presence of monomeric Aβ, but it presents a strong photoluminescence in the presence of Aβ 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.

Photophysical and photochemical properties of a family of isoelectronic tris chelated ruthenium(ii) aza-/azo-aromatic complexes

“…The luminescence spectra are shown in Fig. 3 This is opposite to the trend observed for Re(I) ligands, as [Re(L 1 )(CO) 3 Cl] has greater quantum yield compared to the [Re(bpy) (CO) 3 Cl] (5d 6 ). 38,45 The photo-physical measurements are listed in Table 1.…”

“…Aza-aromatic complexes of ruthenium are extensively used as photosensitizers, for production of H 2 and O 2 from H 2 O, [1][2][3][4][5] and for biological sensing. 6,7 Cyclic azaaromatic complexes of ruthenium are used as sensitizers in dyesensitized solar cells. [8][9][10][11][12][13][14] Aza-aromatic ruthenium(II) complexes are also promising candidates for incorporating into low voltage, single-layer, solid-state electroluminescent devices, such as light emitting diodes (LEDs), as they have high photoredox efficiencies.…”

Ruthenium Red Colorimetric and Birefringent Staining of Amyloid-β Aggregates in Vitro and in Tg2576 Mice

“…42 Aβ fibrils were incubated as reported above. 16 Transmission Electron Microscopy. Two microliters of Aβ sample (100 μM) was deposited on a glow discharged copper grid (Ted Pella 01811) and allowed to adsorb for 1 min.…”

Binuclear ruthenium(II) complexes for amyloid fibrils recognition

“…Transition metal complexes constitute an interesting class of probes exhibiting versatile properties that, due to the rigid coordination framework with possibilities to vary the three-dimensional structure could be tuned for specific tasks [6,7]. Ruthenium(II) complexes, in particular those comprising the dipyrido[3,2-a:2 0 ,3 0 -c]phenazine (dppz) ligand and derivatives thereof, have been intensively studied due to their environmental sensitive luminescence which make them versatile spectroscopic probes for biomolecules including amyloid fibrils [8]. Strongly hydrophobic environment leads to the efficient fluorescence, whereas polarity leads to complete quenching (so called the lightswitch effect [9]).…”