A ratiometric fluorescent sensor with different DNA-templated Ag NCs as signals for ATP detection

Abstract

Content of adenosine triphosphate (ATP) is an essential index in the development of various diseases and even some malignant tumors. Biosensing for ATP with high sensitivity and accuracy is of fundamental importance in both biological research and medical diagnostics. Here we report a ratiometric fluorescent sensor for ATP based on multi-color silver nanoclusters (Ag NCs). This nanosystem contains two core components: a hairpin DNA integrated with an ATP aptamer, an anchor sequence and a special template segment for synthesis of green-emitting Ag NCs; a single-stranded DNA (ssDNA) which is incompletely complementary with the anchor sequence to be a duplex scaffold for red-emitting Ag NCs. Once exposed to the target, formation of the ATP/aptamer complexes opens the hairpin structure and releases the anchor sequence to hybridize with the ssDNA, accompanied by the “turn-off” of the green fluorescence and “turn-on” of the red fluorescence. By measuring the fluorescence intensity ratio of the two signals, we successfully establish a ratiometric sensor which exhibits sensitive and accurate assay performance toward ATP, with the limit of detection (LOD) as low as 0.38 μM. Meanwhile, this ratiometric sensor shows stable recovery in real sample assay, indicating their potential promise in practical applications.