Aggregation-induced emission (AIE)-active fluorescent probes with multiple binding sites toward ATP sensing and live cell imaging.

Aggregation-induced emission (AIE)-active compounds are attractive fluorescent materials for applications in chemical and biological sensing. The AIE effect of such materials amplifies changes in the fluorescence signal due to the physical state transformation from aggregation to disaggregation, which can be employed for detecting various analytes with high sensitivity. In particular, specific bio-active analyte recognition is not only very interesting but also challenging. In this paper, we report a set of novel AIE-active fluorescent probes containing pyridiniums and boric acid groups (TPA-PP, TPA-PPA-1, TPA-PPA-2, TPA-PPA-3), which has been developed for adenosine 5'-triphosphate (ATP) recognition. These probes with two types of interaction modes and multiple connection sites toward ATP molecules are able to selectively discriminate ATP among other bioactive anions with a significant enhancement in fluorescence emission. In particular, in the application of cell imaging, as the number of positive charges and boric acid group increased further, the probes could penetrate into cells, and then enter into the nucleus very specifically. These results clearly demonstrate that the newly developed sensors are suitable for specific tracing of different cell organelles with a height visualization and retention ability. Therefore, all of them are confirmed as promising alternatives for live cell imaging in the future.