A sensitive quartz crystal microbalance assay of adenosine triphosphate via DNAzyme-activated and aptamer-based target-triggering circular amplification

• The method has implemented two kinds of enzymes as a versatile catalyst and aptamer recognition strategy for the sensitive detection of ATP.
• As an efficient mass amplifier, AuNP-functionalized probe was introduced to enhance the QCM signal.
• The utility of this strategy has been demonstrated for the sensitive detection of ATP in cancer cells.

In this work, a simple and novel quartz crystal microbalance (QCM) assay is demonstrated to selectively and sensitively detect the adenosine triphosphate (ATP). The amplification process consists of circular nucleic acid strand-displacement polymerization, aptamer recognition strategy and nanoparticle signal amplification. With the involvement of an aptamer-based complex, two amplification reaction templates and AuNP-functionalized probes, the whole circle amplification process is triggered by the target recognition of ATP. As an efficient mass amplifier, AuNP-functionalized probes are introduced to enhance the QCM signals. As a result of DNA multiple amplification, a large number of AuNP-functionalized probes are released and hybridized with the capture probes on the gold electrode. Therefore the QCM signals are significantly enhanced, reaching a detection limit of ATP as low as 1.3 nM. This strategy can be conveniently used for any aptamer-target binding events with other biological detection such as protein and small molecules. Moreover, the practical determination of ATP in cancer cells demonstrates the feasibility of this QCM approach and potential application in clinical diagnostics.