Fluorescence Lifetime and Smartphone-Enabled Detection of Amyloid-β for Diagnosis and Staging in Alzheimer's Disease

Alzheimer's disease (AD) is characterized by the pathological aggregation of amyloid-β (Aβ) peptides into plaques that drive neurodegeneration and cognitive decline. As Aβ remains the central and pathological biomarker for early and definitive AD diagnosis, there is a critical need for sensitive, accessible, and clinically adaptable detection technologies. Here, we report TZ-48, a fluorescence lifetime-responsive probe designed for highly selective and sensitive detection of Aβ in brain tissue and biofluids. TZ-48 exhibits strong turn-on fluorescence, distinct lifetime signatures, and real-time tracking of Aβ aggregation kinetics. The probe binds Aβ fibrils (Aβf) with high affinity (Kd = 41 nM), exhibits a low detection limit (68 nM), and displays exceptional selectivity over off-target species. TZ-48 crosses the blood-brain barrier (BBB) and enables dual-mode confocal and fluorescence lifetime imaging (FLIM) in AD mouse brains, allowing early visualization and staging of Aβ burden. It also permits quantitative detection of Aβ in serum, distinguishing AD from healthy mice. These findings underscore the potential of TZ-48 as a versatile multimodal probe for disease assessment across tissues and biofluids. To translate this molecular capability into an accessible diagnostic format, we developed ADxFluor, a smartphone-enabled platform that leverages the fluorescence response of the probe for rapid, accurate, and user-friendly assessment of serum Aβ load. Overall, TZ-48 and ADxFluor establish a fluorescence lifetime and smartphone-enabled diagnostic platform for Aβ detection and staging, offering a powerful and accessible approach to advance AD diagnosis, prognosis, and therapeutic development.