Target Recycling Transcription of Lighting-Up RNA Aptamers for Highly Sensitive and Label-Free Detection of ATP

We describe here a target recycling transcription of lighting-up aptamer strategy for detecting ATP in human serums in a label-free means with high sensitivity. ATP molecules specifically recognize the binding aptamer and result in the structure switching of the DNA assembly probes to imitate the target ATP molecule recycling cycles through the toehold-mediated strand displacement reaction, which causes the formation of many dsDNAs containing the RNA promoter sequences for subsequent transcription generation of large amounts of lighting-up aptamers. The organic dye, malachite green, then associates with these lighting-up aptamers to produce significantly enhanced fluorescence signals, which can sensitively detect ATP within a dynamic range from 10 to 500 nM in a label-free way. The sensing approach shows a detection limit of 7.3 nM and also has an excellent selectivity for ATP analogue molecules. In addition, this method can detect ATP molecules in diluted human serum samples sensitively, which proves the promising potential to diagnose ATP-related diseases.