Rational Design of a Dual-Channel Fluorescent Probe for the Simultaneous Imaging of Brain Amyloid-β Plaques and HClO/ClO- in Alzheimer's Disease.

Alzheimer's disease (AD) is the most prevalent form of dementia. The pathological hallmarks of AD are characterized by the presence of amyloid-β (Aβ) plaques and elevated production of hypochlorous acid (HClO/ClO-) in the brain. However, there is a lack of effective tools to image the biological functions of Aβ aggregates and HClO/ClO- in the AD brain. In this study, we presented the first single-molecule fluorescent probe, CTAD-MB, capable of detecting both Aβ aggregates and HClO/ClO-. The design strategy for this probe combines an N,N-dimethyl-phenylcoumarin moiety, which has high affinity for Aβ aggregates, with a methylene blue derivative that specifically responds to hypochlorite. This bifunctional fluorescent probe provided distinct fluorescent signals for Aβ aggregates and HClO/ClO-. CTAD-MB demonstrated completely independent spectral responses to Aβ and HClO/ClO-, offering high selectivity, sensitivity, and rapid response. The probe was successfully employed in imaging the HClO/ClO- stimulated by Aβ aggregates in PC12 cells. Also, it was effectively applied for dual-channel detection of Aβ and HClO/ClO- in the live AD mouse, which could be used to distinguish from the brain inflammation mouse. This insight not only advances our understanding of AD but also provides new avenues for its diagnosis and treatment.