Fluorescent imaging of β-amyloid (Aβ) is one of the most promising methods for Alzheimer’s disease diagnosis. Several fluorescent probes have been reported to detect Aβ both in vitro and in vivo. However, highly sensitive and highly selective probes with low background signals are still greatly needed. Herein, we rationally designed and synthesized a PIET quenched near-infrared probe QAD-1 to detect Aβ. This probe contains BODIPY as fluorophore and tetrahydroquinoxaline as the quenching group. QAD-1 exhibited significant fluorescent switch-on after binding to soluble and insoluble Aβ species, and the probe had the benefit of low background signal to stain Aβ plaques without the need of wash-out procedures in vitro, which was specially found by the fluorescence off–on probe. QAD-1 could identify the overproduced Aβ in transgenic (APP_SWE/PSEN 1dE9) AD mice as early as 6 months old in vivo, which indicated that QAD-1 may be a potential probe for monitoring Aβ species at an early stage of AD.

中文翻译：

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使用基于BODIPY的近红外关闭-开启型荧光探针对β-淀粉样蛋白进行荧光成像

β-淀粉样蛋白（Aβ）的荧光成像是诊断阿尔茨海默氏病最有前途的方法之一。据报道，有几种荧光探针可在体内和体外检测Aβ 。然而，仍然非常需要具有低背景信号的高灵敏度和高选择性的探针。本文中，我们合理设计并合成了PIET淬灭的近红外探针QAD-1以检测Aβ。该探针含有作为荧光团的BODIPY和作为淬灭基团的四氢喹喔啉。QAD-1在与可溶性和不溶性Aβ物质结合后显示出显着的荧光开启状态，并且该探针具有低背景信号，可对Aβ斑进行染色，而无需进行体外冲洗程序，这是由荧光关闭探针特别发现的。QAD-1最早可在体内6个月大时鉴定出转基因（APP _SWE / PSEN 1dE9）AD小鼠中过量产生的Aβ ，这表明QAD-1可能是在AD早期监测Aβ种类的潜在探针。