TICT-activated viscosity sensitive mitochondrial probes for imaging and early diagnosis of drug-induced liver injury.

BACKGROUND

Drug-induced liver injury (DILI) poses a significant clinical challenge, with mitochondrial dysfunction and elevated microviscosity emerging as key pathological features.

RESULTS

We reported the rational design and synthesis of a series of viscosity-responsive fluorescent probes WACn (n = 2, 4, 6, 8, 10), based on a D-π-A architecture utilizing the twisted intramolecular charge transfer (TICT) mechanism. These probes integrated a carbazole-thiophene electron-donating unit and a benzoindolium acceptor modified with varying alkyl chains to tune intramolecular rotation and viscosity responsiveness. Study results revealed that probes WACn (n = 2, 4, 6, 8, 10) exhibited strong viscosity-dependent fluorescence enhancement, robust photostability, low cytotoxicity, and excellent mitochondrial targeting specificity. Notably, probe WAC2 enabled mitochondrial imaging at an ultralow concentration (30 nM) and functioned independently of membrane potential. Besides, WAC2 successfully reported viscosity changes under multiple drug stimulations (PA, H2O2, Cu2+, dexamethasone, erastin, etc.) as well as antifungal drug (nystatin-induced) and inflammation (lipopolysaccharide-induced), both in cells or in vivo. Meanwhile, WAC2 enabled monitor changes in viscosity during APAP-induced drug-induced injury in normal hepatocytes as well as hepatoma cells. Most importantly, it enabled the multi-level visualization of DILI progression in BALB/c mice, including tissue, organ and living levels.

SIGNIFICANCE: Collectively, probe WAC2 provides a powerful platform for real-time, in situ monitoring of mitochondrial viscosity and offers valuable insights for early diagnosis and mechanistic investigation of DILI.