Lysosome-targeted cascade nanoprobe reveals Aβ-induced cholesterol dysregulation via dual-mode imaging in Alzheimer’s disease models

Cascade nanoprobe converts lysosomal cholesterol into dual-mode optical signals • Au-Cu core enables cascade-compatible amplification with cellular operability • Probe visualizes A β /OA-associated lysosomal cholesterol dysregulation in cells • In vivo imaging and MALDI-MSI support brain cholesterol-associated activation Alzheimer’s disease (AD) has been linked to aberrant cholesterol handling in the endolysosomal system, but there are still few analytical tools that show cholesterol dysregulation in living cells and relate it to A β -associated autophagy-related stress responses. Here, we created HBC@Au-Cu, a cascade nanoplatform that targets lysosomes. Within a single nanostructure, this system spatially combines dual-mode optical signaling, Au-Cu catalytic amplification, H 2 O 2 relay, and cholesterol oxidation. We defined catalyst selection at the cascade level instead of choosing the catalytic component only on the basis of peroxidase-like activity. The Au-Cu bimetallic core was chosen after taking into account cytocompatibility, fluorescence transduction compatibility, and catalytic amplification. Cholesterol was transformed into complementary colorimetric and fluorescence outputs within the integrated cascade system, providing linear response ranges of 0–100 μM (R 2 = 0.9955) and 0–10 μM (R 2 = 0.9972), respectively. HBC@Au-Cu increased lysosomal fluorescence in an A β /OA-induced AD-like cellular model, which was reduced by cholesterol-modulating treatments in the same pathological setting. The probe produced increased head-region and ex vivo brain fluorescence in 5xFAD mice, and MALDI-MSI also showed a spatial correlation between probe activation and the endogenous cholesterol ion signal (r = 0.88). All of these findings point to HBC@Au-Cu as a chemical platform that converts cholesterol dysregulation into a quantifiable intracellular phenotype accompanied by p62/LC3-associated autophagy-related stress responses. They also demonstrate the analytical potential of cholesterol-responsive imaging in AD-related models and provide a basis for its future evaluation in early-stage AD assessment. Download: Download high-res image (274KB) Download: Download full-size image