An Autonomous Nonenzymatic Concatenated DNA Circuit for Amplified Imaging of Intracellular ATP.

A robust ATP aptasensor has been successfully constructed for intracellular imaging via the autonomous nonenzymatic cascaded hybridization chain reaction (Ca-HCR) circuit. This compact aptasensor is easily assembled by integrating the sensing module and amplification module, and is furtherly introduced for selective adenosine triphosphate (ATP) assay and for the sensitive tracking of varied ATP expressions in living cells. The ATP-targeting aptamer-encoded sensing module can specifically recognize ATP and release the initiator strand for successively motivating the two-layered HCR (hybridization chain reaction) circuit via the FRET transduction mechanism. The synergistic reaction acceleration of the two HCRs contributes to the high signal gain (amplification efficiency of N2). The whole reaction process was modeled and simulated by MATLAB to deeply explore the underlying molecular reaction mechanism, implying that the cascade HCR is sufficient enough to guarantee the ATP-recognition and amplification processes. The Ca-HCR-amplified aptasensor shows high sensitivity and selectivity for in vitro ATP assay, and can monitor these varied ATP expressions in living cells via intracellular imaging technique. Furthermore, the present aptasensor can be easily extended for monitoring other low-abundance biomarkers, which is especially important for precisely understanding these related biological processes.