Near-infrared squaraine fluorescent probe for imaging adenosine 5′-triphosphate in live cells

Adenosine 5′-triphosphate (ATP), as a “molecular currency” for intracellular energy transfer, not only participates in various physiological activities, but also involves in various pathological processes of living cells. Therefore, the establishment of a simple, rapid, sensitive and accurate ATP analysis method is of great significance for the study of its physiological functions. In this work, we rationally design a near-infrared phenylboronic acid group-functionalized dicyanovinyl squaraine ( SQ-PBA3 ), with which a supramolecular assembly was constructed for fluorescent imaging of ATP. In PBS buffer, SQ-PBA3 changes self-assembly when adding cetyltrimethyl ammonium bromide (CTAB) deriving fluorescence response of SQ-PBA3 to ATP with the maximum emission at 700 nm, due to the specificity of phenylboronic acid to diols and the multiple electrostatic interactions between SQ-PBA3 , ATP and CTAB molecules. Meanwhile, the probe was successfully applied to monitor intracellular ATP level in MCF-7 cells with high sensitivity and selectivity.