Enzyme-embedded ZIF-8/DNA nanocomposite probe for live cells imaging and sensitive detection of ATP

Adenosine triphosphate (ATP) is the direct supplier of energy in almost all biological processes. The intracellular imaging and sensitive detection of ATP will conduce to elucidate its underlying molecular mechanisms of physiological and pathological functions. Herein, a nanocomposite probe was constructed by adsorbing functionalized DNA onto the surface of ZIF-8 pre-embedded with DNA polymerases and nicking endonuclease for live cells imaging and sensitive detection of ATP. The functionalized DNA contained the molecular beacon and recognition probe which with an aptamer sequence, two cleavage sites of nicking enzyme and two template sequences. After uptake into cells, the nanocomposite probe was biodegraded in acid lysosome, releasing the embedded enzymes and surface-adsorbed functionalized DNA. The specific binding of recognition probe to ATP triggered the double-cycle cascade polymerization nicking reaction with the assistance of embedded enzymes, bringing a significant enhancement of fluorescence signal. Based on this, the imaging of ATP in human cancer cells (HeLa, A549 and MCF-7 cells) was successfully implemented. The expression level changes of ATP induced by oligomycin or Ca2+ in HeLa cells could also be efficiently monitored. Furthermore, the sensitive quantification detection of ATP in vitro was achieved with a limit of detection of 7.7 nM. These results showed this enzyme-embedded ZIF-8/DNA nanocomposite probe will be a promising tool for ATP-associated biomedical research.