A selective near-infrared fluorescent probe for detecting hydrogen peroxide in Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder with growing incidence among younger populations, highlighting the urgent need for early and accurate detection of AD-related biomarkers. Excessive production of reactive oxygen species (ROS), particularly hydrogen peroxide (H₂O₂), induces oxidative stress, leading to neuronal damage and death, which implicates H₂O₂ as a potential biomarker for AD. In this study, leveraging the advantages of fluorescence imaging, we developed a novel near-infrared (NIR) fluorescent probe, LDMD-B, capable of selectively detecting H₂O₂ through a boronate-cleavage mechanism that releases the fluorophore LDMD-OH. Upon reaction with H₂O₂, LDMD-B exhibits a strong "turn-on" fluorescence response at 785 nm (λ_ex = 680 nm) with a large Stokes shift (105 nm) and a low detection limit (LOD) of 24.4 nmol/L. The probe successfully visualized endogenous and exogenous H₂O₂ in SH-SY5Y cells, zebrafish, and an APP/PS1 transgenic AD mouse model, effectively distinguishing between wild-type and AD mice. These findings demonstrate that LDMD-B is a promising tool for imaging H₂O₂ in AD contexts and may facilitate early diagnosis and pathological investigation of AD.