Near-infrared multi-functional aggregation-induced emission fluorescent probe for detection of viscosity and peroxynitrite and its imaging application

Viscosity and peroxynitrite (ONOO−) are two crucial elements that influence the operational status of biological processes within living organisms. Their abnormal changes cause metabolic disorders and even diseases. Therefore, it is important to develop a near-infrared (NIR) probe with an aggregation-induced emission (AIE) feature that is capable of dual channel detection of both viscosity and ONOO−. Here, a NIR fluorescent probe LY with large Stokes shift was synthesized in which triphenylamine was conjugated to a pyridinium phenylborate salt. Probe LY with the distorted intramolecular twisted intramolecular charge transfer (TICT) properties is sensitive to systemic viscosity and exhibits enhanced fluorescence emission at the 704 nm peak. On the other hand, the probe is also susceptible to peroxynitrite-triggered borate oxidation, providing an AIE fluorescence-enhanced response at the 639 nm peak. Moreover, with excellent photochemical stability, lower cytotoxicity and a precise targeting ability for mitochondria, probe LY was used to visualize imaging changes in endogenous and exogenous cellular viscosity and peroxynitrite. The imaging results of the probe during ferroptosis confirmed that both the intracellular viscosity microenvironment and peroxynitrite were further overexpressed. Finally, in vivo imaging experiments showed that the occurrence of inflammation was accompanied by an increase in the viscosity and the release in peroxynitrite.