Enzyme-free dual-DNA walker based on catalytic hairpin assembled DNAzyme for sensing telomerase activity

Abstract

Telomerase is a potential tumor biomarker. Herein, an enzyme-free and isothermal fluorescence strategy, dual-3D DNA walker based on catalytic hairpin assembled DNAzyme (CHA-DNAzyme), for ultrasensitive detection of telomerase activity is described. Upon incubation with telomerase, the telomerase primer is elongated to form telomeric repeat sequences (TR). The elongated TR stochastically moves along the predesign track by continuous strand displacement reaction to assemble the intact DNAzyme (CHA walker). Then, the activated DNAzyme autonomously moves along the other track by cleaving DNA hairpins to release fluorescent-labeled DNA fragments from AuNPs (DNAzyme walker). As a result, a large amount of fluorescence is recovered to analyze telomerase activity. The use of CHA walker and DNAzyme walker endows the sensing strategy with high sensitivity and signal transfer efficiency. The strategy exhibits a wide analytical range from 10 to 1000 HeLa cells mL−¹ with a limit of detection of 7 cells mL−¹. The strategy not only can detect telomerase activity in different tumor cells, but also quantifies telomerase activity of cancer cells from accumulated normal cells. In addition, the practicability of the strategy is validated by detecting telomerase activity in human serum.