Rhodamine-Based Fluorescent Turn-On Probe for Facile Sensing and Imaging of ATP in Mitochondria

We have developed a turn-on fluorescent probe ARP-1 as a colorimetric and fluorescent chemosensor for adenosine-5'-triphosphate (ATP) through hydrogen bond interactions. The probe exhibits turn-on fluorescence response to ATP with a 15-fold fluorescence intensity enhancement under 10equiv. of ATP added. The experimental results show that the response behavior of ARP-1 toward ATP is pH independent (pH4.0-8.0). The novel chemosensor has high specificity towards ATP from other nucleoside polyphosphates such as ADP and AMP. The favorable interaction between a triphosphate unit of ATP and N atoms of probe ARP-1 is attributed to H-bonding. Consequently, the enhanced emission and naked-eye changes are attributed to spirolactam ring-opening. It is evident from our findings that the role of the chain length as well as the NH, OH groups and the phosphate group(s) contribute to interaction between the probe and the nucleotide. Cell permeability and selectivity towards ATP was demonstrated in HeLa Cells. Colocalization experiments were carried out with MitoTracker green and ARP-1 showing that the mitochondrion selective imaging ability of ARP-1. The live cell imaging experiments in HeLa cells exhibited high selectivity of probe ARP-1 with fluorescence turn-On response. ARP-1 could also be explored for understanding the cellular functions.