In Vitro Monitoring of NADH Level in Induced NAFLD Cell Model and Diseased Liver Tissues Using an Organoselenium‐Based Molecular Probe Through Fluorescence Imaging

The present work highlights the development of a molecular probe, MQ‐SeZ , bearing a benzoselenazole unit linked to a quinolinium unit through an olefin spacer. The probe is weakly fluorescent, possibly due to its acceptor‐π‐acceptor structural feature. However, in the presence of NADH, a pronounced emission signal was observed at ∼574 nm (λ ex = 543 nm), likely due to the reduction of the quinolinium acceptor unit and subsequent formation of the donor–acceptor system. Consequently, the enhanced fluorescence emission can be attributed to efficient intramolecular charge transfer within the donor–π–acceptor framework. Moreover, the probe exhibited a detection of ∼50 nM of NADH, demonstrating high sensitivity. Owing to its good optical properties, MQ‐SeZ was employed to monitor NADH levels under various intracellular conditions. In HepG2 cells, MQ‐SeZ enabled visualization of altered NADH levels in nonalcoholic fatty liver disease models induced by high glucose, palmitate, and high insulin treatment. Furthermore, the tissue imaging study revealed the elevated NADH level in liver tissue sections from high‐fat‐high‐sucrose diet mice compared with those from regular chow diet controls. Collectively, the current results reveal that MQ‐SeZ can be used as a small‐molecule probe for imaging NADH dynamics and its modulation across diverse pathological conditions.