Rational design of a high-affinity fluorescent probe for visualizing monitoring the amyloid ß clearance effect of anti-Alzheimer's disease drug candidates.

ABSTRACT

Beta-amyloid (Aß), the most pivotal pathological hallmark for Alzheimer's disease (AD) diagnosis and drug evaluation, was recognized by TZ095, a high-affinity fluorescent probe developed by rational molecular design. With a TICT mechanism, TZ095 exhibited remarkable affinity with Aß aggregates (Kd = 81.54 nM for oligomers; Kd = 66.70 nM for fibril) and substantial fluorescence enhancement (F/F0 = 44), enabling real-time monitoring of Aß in live cells and nematodes. Significantly, this work used TZ095 to construct a new protocol that can quickly and conveniently monitor Aß changes at the cellular and nematode levels to evaluate the anti-AD efficacy of candidate compounds, and four reported Aß-lowering drug candidates were administrated for validation. Imaging data demonstrated that TZ095 can visually and quantitatively track the effect of Aß elimination after drug treatment. Furthermore, TZ095 excelled in ex vivo histological staining of 12-month-old APP/PS1 mouse brains, accurately visualizing Aß plaques. Integrating CUBIC technology, TZ095 facilitated whole-brain, 3D imaging of Aß distribution in APP/PS1 mice, enabling high-resolution in situ analysis of Aß plaques. Collectively, these innovative applications of TZ095 offer a promising strategy for rapid, convenient, and real-time monitoring of Aß levels in preclinical therapeutic assessments.