A hemicyanine derivative for near-infrared imaging of β-amyloid plaques in Alzheimer's disease.

The formation of amyloid-β (Aβ) plaques in the brain is one of the main pathological features of Alzheimer's disease (AD). The imaging probes, capable of detecting Aβ deposition, are important tools for early diagnosis of AD. In this article, we designed, synthesized and evaluated a cyanine-based near-infrared fluorescence (NIRF) probe ZT-1 for the detection of Aβ deposits in the brain. The probe had excellent fluorescent properties with an emission maximum above 720 nm upon binding to Aβ aggregates with affinity of 445.0 nM (Kd). Furthermore, ZT-1 exhibited good biostability, photostability, and binding selectivity toward Aβ1-42 aggregates by in vitro fluorescence staining experiments. In vivo NIRF imaging result also revealed that our probe could efficiently differentiate transgenic and wild-type mice. All these studies indicated that ZT-1 is a promising fluorescent probe for Aβ plaques in the AD brains.