Application of a novel coumarin-derivative near-infrared fluorescence probe to amyloid-β imaging and inhibition in Alzheimer's disease

Alzheimer's disease (AD) is an irreversible neurodegenerative disorder. At present, there is no available therapy that can effectively prevent or reverse the progression of the disease, and there are no obvious symptoms in early AD. Therefore, it remains urgent to develop an early diagnosis of AD. Scientists have put forward amyloid-β (Aβ) cascade hypothesis of AD. Aβ accumulation is a main biomarker for the progression of AD. We herein report a functional probe which responds to and inhibits Aβ species (oligomer/fibril). By modifying the structure of coumarin, we designed two multi-functional probes, CouS-1 and CouS-4. An amino-modified benzofuran group was introduced as the electron acceptor, and a lipophilic conjugated thiophene bridged benzidine was introduced as the electron donor and Aβ recognition group as the donor- π-acceptor (D-π-A) backbone. The structure-activity relationship was analyzed. CouS-1 and CouS-4 exhibited responsive enhancement in fluorescence. DLS studies showed their inhibitory effect on Aβ deposits. Both in vivo and in vitro studies proved that our probe could quickly pass through BBB and successfully detected Aβ deposits in early (4 months) and late (10 months) transgenic mouse models. Taken all, we explored the potential of coumarin derivatives-based bioprobes for the early diagnosis and inhibition of AD. [Display omitted] •A functional “D-π-A” NIRF bioprobes based on coumarin scaffold was designed and synthesized (CouS-1 and CouS-4).•The responsive imaging and inhibition towards amyloid-β species were summarized.•Both in vitro and in vivo studies have discussed the potential of CouS-1 and CouS-4 as early diagnosis of Alzheimer's disease.