Ultra-large stokes shift probe enables SIM super-resolution tracking of lysosomal acidification impairment in Aβ trafficking dysregulation during Alzheimer's disease.

Abstract

Lysosomal acidification deficits are increasingly recognized as early events in Alzheimer's disease (AD), yet tools for real-time pH monitoring remain limited. Here, we report AHP, a pH-sensitive fluorescent probe with rapid response (ΔpH ≥0.2), high lysosomal specificity, ultra-large Stokes shift (>240 nm), and excellent photostability for long-term imaging. AHP enabled visualization of biphasic Aβ42-induced lysosomal pH dysregulation-initial hyperacidification followed by pathological alkalinization-directly linking acidification failure to impaired Aβ42 clearance. Dual-channel live imaging showed that reduced lysosomal acidity disrupts Aβ42 degradation, leading to cytoplasmic accumulation and increased toxicity.Using AHP-based high-throughput screening, we identified protocatechuic aldehyde as a lysosomal acidification enhancer and validated its efficacy in restoring autophagic flux. As the probe to achieve super-resolution tracking of lysosomal pH in neurodegeneration, AHP connects pH dynamics with AD pathogenesis and offers a powerful tool for mechanistic insight and drug discovery.This work establishes lysosomal pH homeostasis as a critical target in early AD intervention and highlights the broad applicability of AHP in aging-related disorders.