A PET-Driven Strategy for Ultrasensitive Mapping of Lipid Microenvironment Heterogeneity in Dual Organelles during Metabolic Stress and Atherosclerosis

Abnormalities in the organelle microenvironment and dysregulated lipid metabolism are critically involved in the pathogenesis of various cellular stress responses and diseases. However, the lack of ultrasensitive methods for resolving the distinct lipid environments of multiple organelles simultaneously hinders a deep understanding of disease mechanisms. To address this, we engineered a quinoline-fused Si-rhodol probe DMA-SiRd with an asymmetrically expanded π-conjugation system to facilitate dual-channel, crosstalk-free imaging of lipid droplets and mitochondria through a broad emission shift. Strategic incorporation of a dimethylamino group enabled photoinduced electron transfer (PET), revealing exceptional polarity sensitivity manifested by significant fluorescence lifetime variations. Leveraging fluorescence lifetime imaging microscopy (FLIM) and organelle lipid microenvironment dynamics under several stress conditions were quantified. In atherosclerotic plaques, heterogeneous lipid distributions were detected with therapeutic intervention restoring homogeneity. With two-photon FLIM, low-polarity lipid plaques within the cerebral vasculature of atherosclerotic mice were tracked. In summary, we proposed a novel method to significantly enhance polarity sensitivity by introducing the PET effect, providing new approaches for the design of functional fluorescent probes. The dual-channel functional probe DMA-SiRd stands out as a versatile platform for spatial heterogeneity in lipid organization and dissecting lipid associated pathophysiology, thus offering new perspectives for metabolic-disorder researches.