Vibration-Induced-Emission (VIE) for imaging amyloid β fibrils

This paper discusses the use of N, N'-disubstituted-dihydrodibenzo[a, c]phenazines with typical Vibration-Induced-Emission (VIE) properties for imaging amyloid beta (A beta) fibrils, which are a signature of neurological disorders such as Alzheimer's disease. A water-soluble VIEgen with a red fluorescence emission shows a pronounced, blue-shifted emission with A beta peptide monomers and fibrils. The enhancement in blue fluorescence can be ascribed to the restriction of the molecular vibration by selectively binding to A beta. We determine an increasing blue-to-red emission ratio of the VIEgen with both the concentration and fibrogenesis time of A beta, thereby enabling a ratiometric detection of A beta in its different morphological forms. Importantly, the VIEgen was proven to be suitable for the fluorescence imaging of small Ab plaques in the hippocampus of a transgenic mouse brain (five months old), with the blue and red emissions well overlapped on the Ab. This research offers a new rationale to design molecular VIE probes for biological applications.