Facile design and synthesis of boric acid group based fluorescent probes for monitoring mitochondrial ATP fluctuation.

Adenosine 5'-triphosphate (ATP) is a high-energy phosphate compound that provides most of the energy needed for the physiological activities of organisms. The abnormal fluctuation of intracellular ATP level is closely related to a variety of physiological diseases. So, the monitoring of ATP levels is of great significance for the diagnosis and treatment of diseases. Herein, tetraphenylethylene and triphenylamine fluorophores were employed to synthesize six fluorescent probes with different structures, including TPE-P1, TPE-P2, TPE-P3, TPA-P4, TPA-P5 and TPA-P6. These probes all exhibited the advantages of long-wavelength emission, good biocompatibility and large Stokes shifts. Notably, the nitrogen-containing positively charged site and boric acid group of these probes could be used as ATP recognition groups. Then, the selectivity experiments indicated that TPA-P4 possessed good selectivity and higher fluorescence enhancement degree for ATP compared with the other probes, and was more suitable for detection of ATP. Further, TPA-P4 was successfully applied to the imaging detection of ATP in mitochondria. Importantly, TPA-P4 could also distinguish between normal liver cells (LO2) and liver cancer cells (HepG2) by imaging ATP, which may show great potential applications in tumor diagnosis. It had also been successfully applied to the detection of ATP levels during liver injury and inflammation, which is expected to provide important information for the diagnosis and treatment of diseases in the future.