A Fluorescence Light-Up Silver Nanocluster Beacon Modulated by Metal Ions and Its Application in Telomerase-Activity Detection.

DNA-templated silver nanoclusters (DNA-AgNCs) have been extensively studied in recent years. The enhancement of fluorescence emission from DNA-AgNCs is still being explored. Herein, a study on the fluorescence enhancement of DNA-AgNCs induced by metal ions is reported. The enhancement is greatly dependent on the primary sequence and secondary structure of the DNA strands. Thus, a label-free AgNCs-based molecular beacon (MB) was explored for the detection of telomerase activity. Nonfluorescent MB-AgNCs in phosphate buffer emit dramatic red fluorescence when Mg is introduced, whereas Mg has a limited effect on the weak fluorescence of DNA-AgNCs when the hairpin structure of MB is opened. Telomerase primer can be elongated by telomerase, which results in unfolding of MB in a strand-displacement reaction. On the basis of the different brightnesses of AgNCs produced by the two DNA templates, telomerase activity can be detected. The MB-AgNCs sensing platform provides a simple and low-cost method to detect telomerase activity and shows great potential in the construction of cost-effective probes for biomolecular detection.