Dual-responsive two-photon probe for specific lipid droplets near-infrared fluorescence imaging in the brain of epileptic mice

Abnormal lipid metabolism in glial cells is a key pathological feature of epilepsy. The identification of lipid droplets (LDs) is essential for investigating lipid metabolism, disease progression, and potential therapeutic interventions. Two-photon imaging technology enables real-time visualization of the spatial distribution and temporal dynamics of LDs in epilepsy models. In this study, we developed a novel two-photon excited dual-responsive near-infrared fluorescent probe, CabA, based on viscosity and polarity, to monitor dynamic changes in LDs. The fluorescence of CabA at 670 nm exhibits a significant increase in response to low polarity and high viscosity due to the twisted intramolecular charge transfer and intramolecular charge transfer mechanisms. The LDs-targeting capability of CabA at the cellular level and the process of LDs generation between neurons and astrocytes during the pathological advancement of epilepsy have been validated. In situ synchronous imaging experiments in epileptic and normal mice using CabA revealed abnormal LDs accumulation in the brain during seizures. Two-photon fluorescence imaging further demonstrated LDs accumulation in the brains of epileptic mice at a penetration depth of 100 μm. This study offers a valuable tool for enhancing the understanding of LDs in physiological and pathological processes, potentially aiding in the early diagnosis of epilepsy.