A mitochondria-targeting fluorescent sensor for on-off-on response to Cu²⁺ and ATP in cells and zebrafish

Cupric ion (Cu²⁺) and adenosine triphosphate (ATP) are functionally important in mitochondria and play essential roles in many important biological processes. In this work, a mitochondria-targeting fluorescent molecule Mito-A was used as a probe to detect Cu²⁺ and ATP. The results showed remarkable fluorescence quenching of Mito-A in the presence of Cu²⁺, and then the quenched fluorescence solution gradually recovered due to the ATP binding to Cu²⁺ from the structure of the molecule. Mito-A has high sensitivity to Cu²⁺ and ATP, with limits of detection (LOD) close to 40 nM and 0.43 μM, respectively. Cell imaging experiments showed that Mito-A has good mitochondria-targeting capabilities, and can be successfully employed for imaging Cu²⁺ and ATP in living cells and zebrafish.