Dual-functional fluorescent bio-sensor for detecting ONOO- and polarity for targeted-diagnosis of NAFLD in vivo fluorescence imaging.

BACKGROUND: Alterations in the polarity of lipid droplets as a unique spherical organelle are closely associated with multiple pathological factors such as oxidative stress and ferroptosis. ONOO-, as a type of reactive oxygen species, also plays a crucial role in cellular activities. Accurately monitoring the abnormal changes in ONOO- and LDs in vitro and in vivo environments is crucial to promote the diagnosis of non-alcoholic fatty liver disease (NAFLD).

RESULTS: In this study, a dual-responsive fluorescent bio-sensor PTQ based on triphenylamine groups was devised for monitoring of low - polarity environment and peroxynitrite (ONOO-) in water bodies and living organisms. PTQ exhibited high sensitivity (LOD = 1.92 nM), strong fluorescence signal and high quantum yield (57.76 %) in low polarity media. Concurrently, it exhibited a markedly enhanced fluorescence response to ONOO-, coupled with exceptional selectivity, a low detection limit (4.97 nM), and excellent biological imaging capability. On this basis, PTQ was effectively employed for targeted monitoring of LDs and detection of endogenous ONOO- in HepG2 cells. PTQ was applied to the bio-imaging of NAFLD mouse models by monitoring ONOO- and LDs.

SIGNIFICANCE: In summary, PTQ not only serves as a valuable instrument for investigating polarity and the involvement of ONOO- in NAFLD, but also has the potential to become a powerful molecular imaging tool for exploring the complex biological effects in various biological environments.